Hello.
I understand that you are worried and concerned about your mother, it must be difficult for you as well.
It is very important to deal with the situation as early as possible. Since depression is present, it is very important that your mother has a strong support system or someone with whom she can talk to or share her feelings. Depression at its extremity has led her to cut her hand and harm herself.
It is equally important to understand about the voices that you have mentioned, it could indicate something.
Next Steps
As early as possible it is important to meet a psychiatrist and understand the situation better.
Health Tips
Support system is very much required as of now. I understand that you are staying far from home, however I would encourage you to speak to her as much as you can, when you can. Or encourage your father to understand the situation better so that he could be a support to your mother.