Q. Can my mum go with my husband ie her son-in-law for umrah ? And her only sister stays with her and has no husband or children. Can she go with them as well ?
A. A mother-in-law is a Mahram (prohibited in marriage). A mother-in-law’s sister is not a Mahram (not prohibited in marriage).
Hence, it will be permissible for ones husband to travel as a Mahram for his mother-in-law provided that there is no fear of Fitnah (temptation) between them. However, it will not be permissible for him to travel as a Mahram for his mother-in-law’s sister.
Allah Ta’ala Knows Best
Mufti Ismaeel Bassa