Does the mother have the right to custody of her children after the father's death, and does she have the right to take them with her and travel with them even if she wishes to marry?

Child custody belongs to the mother as long as she does not remarry. Then it transfers to the paternal grandmother, then the maternal grandmother. The best interest of the child must be considered in all circumstances. The mother is permitted to travel with her children as long as no harm results from it.