الجواب حامدا و مصلیا
It is permissible for a person to go on Haj and Umrah with his wife and the mother in law but if the sister in law is an adult and there is no other Mahrem (a male whose marriage is unlawful to her) to accompany, it is not permissible for her to travel with her brother in law and it is necessary to abstain from it.
