About education loan

Respected sir, I am Sabarish M from the state of Tamil Nadu from Vellore district. My father is an retired indian army pensioner who passed away on 18-FEB-2017 due to cancer. Now my mother is getting the indian army widow pension. In the year 2012 back my father had signed as a guarantor for education loan for his friend's daughter, and he never said a word about his guarantee siganture to any one in our family. There is balance of Rs13000 in his account, so we had filled the death claim form to claim the money as we are the legal heirs, the bank manager suddenly told us that my father is a guarantor for education loan so my mother has to sign some document to claim the money. Since the man is not paying the loan properly, whether is there any chance that my mother will be included will be included as a guarantor and she has to pay the loan if he fails to do repay the amount. Kindly give me some suggestions. Thank you Name-Sabarish M Mail [deleted]