Is there a supplication that would bring peace to the heart of a mother afflicted with fearful delusions of harm or murder, and deliver her from her fear?

The most beneficial thing for a person in attracting blessings and repelling distress is to turn to Allah with sincerity and devotion, by performing the obligatory duties and avoiding prohibitions, and by regularly engaging in remembrance (dhikr), reciting the Quran, performing supererogatory prayers (nawafil), and reciting the reported supplications for dispelling worries. Among these are the supplication "O Allah, I am Your servant, son of Your servant..." and the supplication for the distressed "O Allah, I hope for Your mercy...". Therefore, the questioner should turn to Allah in supplication for her mother, especially during the pre-dawn hours and after prayers.