Is a woman whose husband has passed away obligated to observe her 'iddah in the marital home, or is it permissible for her to move to the home of one of her children so that she does not remain alone, even if she is over eighty years old?

A woman whose husband has died must not leave the house where she received the news of his death, whether she is old or not. The proof for this is the narration of Furay'ah bint Malik, when she asked the Messenger of Allah, peace and blessings be upon him, if she could return to her family. He said to her: "Stay in your house until the prescribed term is fulfilled." So, she observed her iddah (definition) there for four months and ten days. As for her leaving for some of her needs and returning to her place of residence at night, this is permissible out of necessity.