This is really not a good situation for your cousin and I would suggest that she get an attorney as soon as she can  - like yesterday - and have the attorney facilitate her turning herself in.  The issue as to her drinking or being drunk at the scene can be a problem if there is enough evidence to prove it but if there are no blood or breathalyzer tests then she has some issue with actual proof rather than circumstantial evidence.  But leaving the scene of an accident is a crime in and of itself and if her license is suspended it makes me wonder what for and if she is on probation for anything.  All that will be taken in to account when the matter is adjudicated.  Get her help.  Now.