For legal advice it’s better to talk with a lawyer
Tell the lawyer with full stories/all details since no one can really help here for such issues
If they are charged or ticketed with anything related with the car like insurance/tags only, then Avis may deal with those directly on your behalf.
if they are charged or ticketed with marijuana or other things under local law, there will be certain consequences that are out of rental companies control.
So lawyer or legal aid will probably be the only option