73 year old taking care of 94 year old father. What resources are available?

My 73 year old dad (who recently lost his wife, my mom) has been left to take care of my 94 year old year old grandfather who is in failing health and can't really be alone. His siblings have abandoned their father, so my Dad has to check on him, prepare his meals and ensure he has his physical needs met each day. The 94 year old still lives alone. I'm a 30 year old and I've never dealt with aging care before, but my dad can't go anywhere or do anything because he's stuck with my grandfather. I know, this is common. What resources are available? How much, can anyone estimate, it would cost for someone to come to the house daily to care for my grandfather? for a couple hours, max.