What is the ruling of Islamic law regarding a gift that was completed and fully taken possession of during the lifetime of the donor, and then the heirs of the donor's heirs demanded its annulment 52 years after the gift?

If the gift was executed during the lifetime of the donor and then she passed away, none of her grandchildren have the right to demand its annulment. This is affirmed by the fact that the obligation to ensure equality among children in a gift applies specifically to children of the same degree, and grandchildren are not included with them in this regard.