Because of the housing bubble and not knowing what their local housing market is like I hesitate to mention this but you can take this as more of a brainstorming idea than a real suggestion.

When my in-laws had their modest retirement home built they had an apartment designed into the back of it so they would have some retirement income. This way the house would basically generate enough income to pay for the maintenance and property taxes so that they would have their housing covered as long as they were able to live independently. The plan was that if they ever need to move to a nursing home they could then sell the house to pay for their nursing home. Your friends in-laws could do much the thing if affordable duplexes are available in their area.

For what it is worth, I suspect that you haven’t gotten the whole story.

Greg