Legal action if father took loan and gave cheque in mother's name

My father taken a personal loan of 5 lakhs against my mother named blank checks in 2009. The person deposited the check in bank. But these checks are no longer acceptable in bank because bank didn't accept the pre 2010 checks. Also I already done the stop payment of checks 2 years back. As loan is taken by my father not my mother. Now that person is threatening us to file the case against my mother. Does the person is eligible to file the case against my mother? If yes please guide us what to be done in this case?