How do we start the process of reverse mortgage?

I am trying to see how my mom goes about applying for a reverse mortgage. She is a widow and the insurance money my father left her is getting low. She needs money to live on and we are talking about this. She wants to take out a life policy that we could use to pay off the reverse mortgage in the event of her death . How could we figure how much we would need? I thought that would be tricky. The home is worth 150,000 but the land it sets on is worth alot more. She wants to be sure that we can use insurance to pay it off so it doesn't interfer with our inheritance. There is other land her to that is on a separate plot. I am hoping you can help me figure out how I would begin to know how much I would need worse case .