If your mother is the only legal heir to succeed to the estates of deceased father then she first has to obtain legal heirship certificate from revenue department and after that she has to submit an application to the revenue department along with the death certificate and the legal heirship certificate to transfer the revenue records to her name.
Subsequently she can apply for name change in property records, electricity connection, water supply etc.
There's no necessity to transfer the property through registration department by registering the same on her name.