Legal Question in Civil Litigation in Maryland

Maryland has a statute of limitations that prevents most suits for negligence more than three years after the incident occurred. Based on the ages in your scenario, it sounds like more than 3 years have passed.

Aside from the timing issue, a non-driver is not automatically "on the hook" simply because they gave the keys. The law does have theories of negligent entrustment which in appropriate circumstances may allow for suit against a person who handed over the keys. However a negligent driver who was injured is in a different position than a passenger or third party who suffered loss. Because Maryland has mandatory insurance, auto insurance usually is a factor in auto accident cases as well.

Keep in mind that these types of claims are very fact specific and an online post will not offer a detailed legal analysis of the merits of your claim against the car owner. If this has not already been litigated (it isn't clear whether the debt is from a judgment or something else, who was injured and what insurance coverage was available) you may want to consult an attorney.