Should he stay in his home or leave?

Well, you live near an active lava flow, that can happen.

It’s not like he’s bitching and moaning about it. He said he’s happy to have had the time he did, and he’s figuring out what to do next. Good for him.

Well it did give him 30 years warning.

I wonder what happens if you have a mortgage on a place like this? The bank most likely has no interest in foreclosing, what with it now being uninhabitable and all.

In fact - who owns the acreage when privately-own land is run over by lava? I mean, it’s not like it’s valuable, or buildable any time soon…

Good question.
I know in LA, if you were stupid enough to build a house on the edge of a cliff and it was destroyed by mudslide or earthquake, you legally lost the house AND the land, so you had nothing left to sell or re-build upon.
So, assuming the lava stops and cools in a few generations, would this land again be for sale by the government and not owned by the previous owner? You could make a case that this was “new land” and the previous lot is several feet below ground.