There are some legal aspects to consider. First, who is on the title of the vehicle? Probably the mother. Next, who is the car registered to? Probably same. Next, who is paying the insurance? If not also your mother, then there could be some legal wranglings associated with a verbal contract between your mother and the friend. If all three are in her name, it almost certainly will be seen in court as your mother letting the friend borrow the vehicle.

She needs to recover this vehicle asap. if the other person has an auto accident in the vehicle, your mother will eventually be liable.

Its not only the late payments that should concern you. its liability.

If the car is in her name then legally it belongs to her and the late payments are, aside from the obvious problems with holds placed on her funds, likely trashing her credit rating as well. She would be better off taking it back from the bum 'friend' and making the payments herself. If the friend refuses to return the vehicle, well, that qualifies as grand theft auto right there. Give the cops all the information and let them handle this 'friend'.