While direct mail can certainly convert well if you know how to do it properly, why don't you focus on inbound channels?

I told her in the past I'd like to help her not lose her house.  

Unfortunately, the parents didn’t have a will, and now the adult child is concerned about what to do with the house.

Have you thought about what you are trying to do here? 

@April Birdsong  check the abandonment laws in your state for what you can do with property.

One way that popped in my head is you master lease it to her mother for a low dollar and let her sublet it. 

Cedric  yes, do not do it, you gain nothing from doing it.

Anything above that reduces her $15M lifetime exemption.

Have her move out (or sign a lease).

I have a friend who is looking to move from her rental home to her first home purchase, and I wondered if we could buy a small multi-family home with her living in one unit and STR the other unit/s.