Typically with that amount of debt stated to be owed they would need a signed agreement in order to hold anyone liable for the loan. You could dispute the debt with credit bureaus if they are reporting it on your mother's credit. It might not take care of the issue. You might have to sue them for violation of the Fair Credit Reporting act if they are reporting and don't take it off and you believe it is not valid. If they sue your mother on this then you could defend the action in state court.