If you haven't done it yet, your first order of business should be to check with the NYC authorities and unravel what went wrong with the disrupted benefits. Arm yourself
It is hard to know whether you have been legally appointed his power of attorney -- not all stationery store documents will do the job. But your father's debts should remain his debts. In general, you will be personal liable for debts you officially incur on his behalf only if you:
with patience, perseverance, and politeness. Getting to the bottom of the mistake will likely require all of them.
- agreed in advance to be personally responsible, such as by co-signing or guaranteeing a particular transaction
- are liable for the debts because of another legal relationship that results in a duty of support, such as you claim your father as a dependent
- negligently caused the debt, or
- acted beyond your legal authority as guardian or conservator in incurring the debt.