Hearing negative voices. All the time.

My mother is hearing negatives voices, which vary from a person crying, to continuous hitting of objects, or someone shouting or since we live in a joint family some one bitching about her. From my point of view this could be due to her previous emotional stress as many family member sometimes have done back bitching about her which i have also heard, but sometimes she hears them even when they are not there or if someone is talking then if she hears some words, her definite conclusion is that they are back bitching about her only. Also a 2-3 years back my father was very rude to her for about a year always shouting at her,at thattimethere was an episode where she was very emotionally traumatized and accused my father that he has installed cameras in house of which the family members have access and they continuously see her. But my father had done no such thing. She also sleep disorders for which treatment is going on. She is always insecure that everyone is watching her all the time.