How can I find out what Medicaid will pay for?

If you are wondering what Medicare covers, here is an excellent list source https://www.medicare.gov/coverage/is-your-test-item-or-service-covered.html

As for Medicaid, it all depends on what programs are offered in your State.

I'm not sure about your question --- Medicare or Medicaid? If your Dad can afford assisted living, I'm guessing you are asking about Medicare. (Medicaid is for those without financial resources). Medicare doesn't pay for long term care. That includes assisted living and nursing homes.
Since there are financial resources held by your Dad, you might start with an assessment from an in-home health care agency. You may be able to bring in someone for 4 hours a day to help your Dad get showered, dressed, moved etc. By observing their techniques, you may be able to better handle things when they aren't with you. You can alos begin to visit assisted living facilities in your area. Each place offers different environments and has different positives/negatives. That way, you will have some direction when it is time to make that decision. It takes a few visits to be sure which one is best for your Dad, so allow time for this process.