Is the house truly owned by the mother after it was transferred to her ownership by her mother, or does it still belong to the father, and who among them is in the right? And is there any sin upon the mother or the grandmother, and how can this dispute be resolved?

The ruling on the grandmother writing the house in the mother's name varies depending on the situation:

1. If the house was taken possession of during the grandmother's lifetime and while she was healthy (a gift): The giver must act justly between their children; otherwise, the gift is invalid unless there is a legitimate شرعي justification. The mother's service to her mother and siblings is not considered a justification for preferential treatment.

2. If the house was taken possession of during the grandmother's death sickness or after her death (a will to an heir): A will to an heir is not valid unless all adult, sane heirs agree to it. The mother's service to her mother and siblings does not justify validating the will without the heirs' permission.

Additional notes:

It is not permissible to take payment for serving one's parents. Insulting and demeaning the mother is among the most severe forms of disobedience (عقوق). Suing parents is not considered disobedience if the child is not unjust. It is advisable to refer the matter to the Sharia court for consideration.