Your mom and dad can get their own credit reports done, they can give you a copy of their reports.
You can go to the recorder of deeds at the county court house to see if there is any liens.
Unless they have been sued and someone took them to court ( they would have been served notice) there should not be a lien.
There is nothing you can do to stop your parents from borrowing money as long as they are of sound mind. You can sit down with them and help them work out a budget.