A sister inquires about the obligations of a widow.
The Ahaadeeth clarify the prohibitions that should be observed by a widow during ‘Hidaad (prescribed mourning period during which a widow does not adorn herself and keeps to the home of her deceased husband). She is required to do five things:
First, she should remain in the house where she was living when her husband died until the end of her `Iddah (woman’s prescribed waiting period after divorce or widowhood), which lasts for four months and ten days , unless she is pregnant. In this case, her `Iddah comes to an end when she gives birth to her child, according to Allaah’s Statement سبحانه وتعالى,
وَأُولَاتُ الْأَحْمَالِ أَجَلُهُنَّ أَن يَضَعْنَ حَمْلَهُنَّ
And for those who are pregnant (whether they are divorced or their husbands are dead), their ‘Iddah (prescribed period) is until they deliver (their burdens)
Surah aţ-Ţalāq (The Divorce) – سورة الطلاق [65:4]
She should not leave this house  except in case of necessity, such as going to the hospital if she is ill, buying food from the market if there is no one to do this on her behalf, if the house is demolished, or if there is no one to stay with her and she is afraid to stay alone. There is no harm in going out in these cases of necessity.
Second, she should not wear beautiful clothes, whether they are yellow, green, or other bright colors. She is only to wear plain clothes, whether they are black, green, or any other color. What matters is that the clothes should not be attractive, according to the orders of the Prophet ﷺ.
Third, she should avoid wearing jewelry such as gold, silver, diamonds, pearls, and so on, whether in the form of necklaces, bracelets, rings, etc. until the end of the `Iddah.
Fourth, she should avoid wearing fragrances, whether incense or any other kind of scents, except at the end of her menstrual period; then, there is no harm in using some incense.
Fifth, she should avoid Kohl (antimony powder eyeliner) and other cosmetics or beautifiers that call attention to herself. However, there is no harm in using soap and water to wash herself.
These five things should be observed by a widow. 
However, the superstitions of some laypeople, such as a widow being not allowed to speak to anyone, talk on the telephone, wash only once a week, walk barefoot at home, go out in the moonlight, and so on are all baseless. She may walk barefoot or use footwear at home, she may cook for herself and her guests, she may walk in the moonlight whether on the roof or in the garden of her house, she may bathe whenever she wants. Also, she may talk to whomever she wishes, provided that the talk involves nothing suspicious, she may shake hands with women and Mahaarim (male relatives unlawful for marriage) but not anyone else, and she may remove her Khimaar (veil covering to the waist) if there is no one present who is not Mahram. However, she may not use henna (a plant that produces a reddish-orange dye), saffron, perfume on clothes, or aroma in coffee, because saffron is a kind of perfume. It is also impermissible for her to entertain marriage proposals, but there is nothing wrong in indirect hints. As for explicit engagement proposals, they are not allowed. May Allaah grant us success.
 As Allaah سبحانه وتعالى states in the Qur’aan,
وَالَّذِينَ يُتَوَفَّوْنَ مِنكُمْ وَيَذَرُونَ أَزْوَاجًا يَتَرَبَّصْنَ بِأَنفُسِهِنَّ أَرْبَعَةَ أَشْهُرٍ وَعَشْرًا
And those of you who die and leave wives behind them, they (the wives) shall wait (as regards their marriage) for four months and ten days
Surah al-Baqarah (The Cow) -[سورة البقرة [2:234
 As comes in the following Hadeeth:
زَيْنَبَ بِنْتِ كَعْبِ بْنِ عُجْرَةَ أَنَّ الْفُرَيْعَةَ بِنْتَ مَالِكِ بْنِ سِنَانٍ، وَهِيَ أُخْتُ أَبِي سَعِيدٍ الْخُدْرِيِّ أَخْبَرَتْهَا أَنَّهَا، جَاءَتْ رَسُولَ اللَّهِ صلى الله عليه وسلم تَسْأَلُهُ أَنْ تَرْجِعَ إِلَى أَهْلِهَا فِي بَنِي خُدْرَةَ وَأَنَّ زَوْجَهَا خَرَجَ فِي طَلَبِ أَعْبُدٍ لَهُ أَبَقُوا حَتَّى إِذَا كَانَ بِطَرَفِ الْقَدُومِ لَحِقَهُمْ فَقَتَلُوهُ . قَالَتْ فَسَأَلْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم أَنْ أَرْجِعَ إِلَى أَهْلِي فَإِنَّ زَوْجِي لَمْ يَتْرُكْ لِي مَسْكَنًا يَمْلِكُهُ وَلاَ نَفَقَةً . قَالَتْ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ” نَعَمْ ” . قَالَتْ فَانْصَرَفْتُ حَتَّى إِذَا كُنْتُ فِي الْحُجْرَةِ أَوْ فِي الْمَسْجِدِ نَادَانِي رَسُولُ اللَّهِ صلى الله عليه وسلم أَوْ أَمَرَ بِي فَنُودِيتُ لَهُ فَقَالَ ” كَيْفَ قُلْتِ ” . قَالَتْ فَرَدَدْتُ عَلَيْهِ الْقِصَّةَ الَّتِي ذَكَرْتُ لَهُ مِنْ شَأْنِ زَوْجِي قَالَ ” امْكُثِي فِي بَيْتِكِ حَتَّى يَبْلُغَ الْكِتَابُ أَجَلَهُ ”
Zaynab bint Ka’b ibn ‘Ujrah reported that al-Furay’ah bint Maalik ibn Sinaan, the sister of Abu Sa’eed al-Khudri, told her that she came to the Messenger of Allaah ﷺ and asked him whether she should go back to her people among Banu Khudrah. Her husband had gone out in pursuit of some rebellious slaves of his, and when he caught up with them at the edge of al-Qadoom, they killed him. She said: “I asked the Messenger of Allaah ﷺ whether I should go back to my family, because my husband had not left me a place to live that belonged to him, or any money for provisions. The Messenger of Allaah ﷺ said yes, so I started to leave, and I had reached the hujurah (room) or the Masjid, when the Messenger of Allaah ﷺ called me or told someone to call me. So I came back, and he asked me, ‘What did you say?’ I repeated the story I had told him about my husband. He said: ‘Stay in your house for the specified length of time.’ So I spent my ‘iddah there, four months and ten days.
Jami` at-Tirmidhi 1204
 Umm ‘Atiyyah reported that the Messenger of Allaah ﷺ said:
لاَ تُحِدُّ امْرَأَةٌ عَلَى مَيِّتٍ فَوْقَ ثَلاَثٍ إِلاَّ عَلَى زَوْجٍ أَرْبَعَةَ أَشْهُرٍ وَعَشْرًا وَلاَ تَلْبَسُ ثَوْبًا مَصْبُوغًا إِلاَّ ثَوْبَ عَصْبٍ وَلاَ تَكْتَحِلُ وَلاَ تَمَسُّ طِيبًا إِلاَّ إِذَا طَهُرَتْ نُبْذَةً مِنْ قُسْطٍ أَوْ أَظْفَارٍ
“A woman must not observe mourning for one who had died for more than three (days) except for four months and ten days in the case of her husband. And she must not wear a dyed (colored) garment except one of ‘Asb (type of garment made of dyed yarn), or apply Kohl (in her eyes), or touch perfume except a little Qust or Azfaar (types of perfumes), when she has been purified (after her courses).”
Saheeh Muslim 938 c