Is the wife sinful if she is unable to pay the share of her deceased husband's mother from her son's inheritance, and she asks the husband's mother to undertake the procedures of selling the apartment to obtain her share?

The deceased's wife does not incur sin if she does not give the mother the value of her share in the inherited house, as long as she does not prevent her from accessing her right and has offered to sell the property. The consent of the remaining heirs is required, and the guardian of a minor acts on behalf of the minor. If the heirs refuse to divide the inheritance and do not give the mother her right, they are compelled to sell in order to remove the harm from the mother. Ibn Taymiyyah said: "That which cannot be physically divided, if one of the partners requests its sale and the division of its price, it is sold and its price is divided." And in Al-Rawd al-Murbi', "And whoever calls his partner in it to sell, he is compelled. If he refuses, the judge sells it on their behalf, and divides the price between them."