Is it permissible to force the fiancée to accept the residency of the sick and elderly mother in the marital home, despite her refusal?

Righteousness towards the mother is among the most obligatory duties and greatest acts of worship, while disobedience to her is among the gravest of sins. All children must care for their mother and fulfill her rights. If your brothers refuse to host her in alternation, then you must house your mother in your home and convince your fiancée of this. If she does not agree, then you must leave her and seek someone else.