Is it permissible to stay with the children of the uncle—three girls and a young man who is 18 years old—to take care of them while their mother, whose husband has passed away, is absent for two weeks to perform 'Umrah?

It is permissible for you to stay with your female cousins and take care of them in their mother's absence, provided you adhere to the hijab and avoid mixing with the male cousin. The male cousin must not spend the night with you, nor be in seclusion with you, nor see from you what Allah has forbidden. He should not enter upon you except after seeking permission and your veiling, and without any seclusion occurring. He should not speak with you except in what is proper, without softening the voice or being submissive in speech. For the Prophet, peace and blessings be upon him, said: "Beware of entering upon women."