Is a widow who is the custodian of a mentally incapacitated minor entitled to remain in the marital home despite owning another residence, and are the heirs entitled to demand rent from her or evict her from it?

All wealth left by the deceased is part of their estate and is rightfully due to their heirs, according to the Prophet, peace be upon him: "Whoever leaves behind wealth, it is for their heirs." This includes the marital home. The wife does not have the right to reside in it after her waiting period (iddah) ends, except with the permission of the heirs, because it is shared property among them. The heirs have the right to prevent her from using it. So, either she resides in the house for a period proportionate to her share and then vacates it, or it is sold and its price or rent is divided among them, each according to their share. It is advisable to consult Sharia courts regarding inheritance matters.