While i don't know all of the circumstances present in your mother's life and I am assuming she actually is eligible for citizenship, I will say that the N-400 "Application for Naturalization," does allow for a waiver of the English and U.S. civics and history requirements based on disability or impairment.
Your mother should definitely consult with a reputable immigration attorney before filing an application for more guidance.
This posting is for informational purposes only and does not create an attorney-client relationship.
The first thing that you need to look at is exactly what test your mother needs to take. There is a special shorter test for applicants over the age of 65 and those who have reached certain ages and been residents for a certain period of time can take the test in their native language.
if your mother has a medical condition which prevents her from memorizing the information needed to pass the test, she can apply for a medical waiver. This must be done in conjunction with the filing of her application for naturalization and will require certifications from her treating physicians. It is a complicated process can be done if handled appropriately. I suggest you schedule a consultation with an experienced immigration attorney who can review your mother's situation and advise you as to the options available to her.