Is there any assistance I can get to help my dad pay his rent in a mobile home park?

I would look for elder assistance through your state's Web site - generally under Aging Services. There should be some contact information to use as a starting point. It sound like, if he's not already, he should be on Medicaid. Good luck.
Carol

As Carol suggested, the best place to start would be you local county Area Agency on Aging. They are a clearinghouse for resources and may be of great help in matching your dad with services available at the state, county, and even city level.

Is your father a veteran? If so look on this site or do a search for a benefit called "non-service connected basic pension". This may provide him with thousands of tax-free dollars per year.

Medicaid may also be a good possibility as all of his medical would be paid for (including his Part B premium of $96/m) freeing up money to be spent otherwise.

Rent, utility, food, and transportation assistance should all be available to him if he qualifies.

Would he consider a roommate?
Good luck.