It sounds like your mother has some sort of psychotic disorder if she’s still hearing voices. It may be schizophrenia or bipolar or dementia. Here is some reading:
and
Here are some resources - do you have other family members that can help you. Educate everyone, and keep a journal about your mother’s behaviors and beliefs so that you can share it with the mental health professionals.
Study this document:
FIRST Aid for Psychosis
http://www.schizophrenia.com/sznews/archives/005561.html
How to get help:
Here is a good place to get your father to, if you can:
I recommend you watch these videos:
I Am Not Sick, I Don’t Need Help! - Dr. Xavier Amador - Pt. 1
and
I Am Not Sick, I Don’t Need Help! - Dr. Xavier Amador - Pt. 2
