My father died 31/7/2018, some person file suit for money recovery

My father die on 31/7/2018. Some person file suit of recovery of money 500000/-.he submit one blank cheque of my father and additionally one land record for his proof. But the land already in dispute.he say in suit they borrow money for his medical expances. But we dont borrow any money from the plaintiff. As per legal heir me and my mon as defendants. They ask me to repay that. Wedont sign any agreement to plantiff. What we do sir