Dad is still feeling sorry for himself after losing his well paying job. I have been down that road myself several times (always laid off with lots of other people - not fired), so I understand how he feels, but self pity doesn't pay the bills. If he's not going to stop spending (clearly he's not), Dave's comment about "earning more" is the only answer. He can get Second Career counselling where people like Dad are interviewed, counselled, and given training for high demand jobs, all while getting paid. He can also get assistance with resumes, covering letters and job interviews at no charge. Yes, finding work when you are older is difficult, but it is not impossible. Again, I speak from experience.
Don't bail Dad out - you are rewarding bad behaviour. You will pay dearly and in more than the financial sense. 
One thing I don't understand - what financial institution gave a man with no job and a terrible credit rating (utilities threatening to cut service) the loan for a new truck?