When one cannot pronounce letters correctly during Salah
You have to teach your mother whatever she can learn from the Qur’an and different matters of her Din (religion). On the other hand, your mother is not to be blamed for being unable to pronounce some letters correctly. (Part No. 5; Page No. 349) This is because Allah (Exalted be He) says:
So keep your duty to Allâh and fear Him as much as you can
Allâh burdens not a person beyond his scope.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.