What is the solution for my mother who repeats her prayer multiple times because she cannot remember the number of rak'ahs, even though her prayer might have been valid?

If the mother is not frequently assailed by doubts and she doubts having omitted a pillar during prayer, she should perform it. If she doubts the number of cycles (rak'ats), she should build upon the lesser number. If the doubt occurs after the prayer has concluded, she should disregard it. However, if doubts frequently assail her, she should disregard them. If she can use a method to accurately count the rak'ats or get assistance, she should do so. She should be advised to stop repeatedly redoing prayers because it reinforces obsessive thoughts (waswas).