You need to contact his prescribing physician, let him/her know about the job situation, insurance, etc., and ask for possible reduction in fees. Your Dad needs to be properly managed in this withdrawal as you should not stop taking xanax abruptly, but need to taper down slowly. The Dr. will set up a schedule for him.
There are several good sites on xanax withdrawal - Dr. Ashton is a good source of information of benzo withdrawal. The information will be useful as you help your Dad.
Check the area for free clinics, too. Does he qualify for medical disability through your state? Perhaps a family crisis center in your area could help? Does your city offer assistance for seniors?
Your Dad is lucky that he has you for support. He'll need it during this difficult period.
Good luck...
How long hes been on it and was he using it reguraly? The only way to reduce withdrawal symptoms is to gradually decrease the drug. Your only way is to somehow find the money, go to doctor and get more xanax and reduce it slowly. Otherwise side effects can't be nasty. Many ppl end up in emergency from cold turkey benzo quitting.