Is it permissible for the mother to prevent the paternal grandmother of her only son from seeing him if the grandmother mistreats the mother and the grandchild?

The mother of the child is not permitted to prevent his grandmother from seeing him if she requests it, as that constitutes the severing of kin ties. The grandmother is in the same position as the mother in terms of dutifulness and maintaining kinship. Al-Qurtubi said: "Grandfathers are fathers, and grandmothers are mothers." The mother is advised to reconcile with the child's grandmother, treat her with kindness, and overlook her mistakes, as this is among noble character traits and carries great reward. Allah Almighty says: "And not equal are the good deed and the bad. Repel [evil] with that which is better; then abruptly your enemy will be as if he were a devoted friend."