All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

If a person is residing in a place where he is unable to practise the rites of his religion, he is obliged to move to a safer place where he can worship his Lord and practice the rites of his religion, especially the prayer, which is the greatest pillar of Islam after the two testimonies of faith.

Therefore, if the sister you are inquiring about is able to move to another house where she will be able to perform the prayer, like the house of her parents, or one of her brother's houses, or the house of one of her Mahaarim, which is the plural of Mahram (i.e. a spouse or a person whom one is permanently prohibited from marrying due to suckling, marital, or blood relations), then she is obliged to move.

However, if she is unable to move and there is a mosque beside her where the five daily prayers are performed, then she should perform the prayer in the mosque. If this is not possible as well, then she should perform the prayer in her grandmother's house secretly in a way that she will not be noticed. For instance she may enter her room and lock the door, and then perform the prayer, and the like. However, she is not exempted from performing the prayer, and she may take advantage of the laws of the country where she resides where freedom of belief and worship are guaranteed and protected. Therefore, she may seek the help of the authorities who will enable her practice her religion in her grandmother's house.

For more benefit on residing in a non-Muslim country, please refer to Fatwa 86405.

Allaah Knows best.