You have every right to sell your own property as per your wish .Now a case is pending before the court so better to dispose the suit immediately . So file an application for speedy disposal before that court, mentioning that you are at the age of 85 need the urgency to dispose the case .Or file a writ petition before high court for the same purpose.If you are not a party in the suit then file an impleading application in that suit. if your life has more threat from daughter in law then file a petition under Domestic Violence Act 2005 for getting a protection order .