So dad was laid off at age 64, has no pension, RRSP, or other savings, and a house that still has a 40% mortgage on it? That is the almost the height of financial irresponsibility - which would be buying a new truck. Let dad get a wake-up call by having his truck repossessed before doing anything.
   
Helping financially would only be enabling his behavior, especially if you do that now. At least wait until dad is forced into bankruptcy before buying the house at auction. If you do, be prepared to pay cash, and to let them live in it rent-free for the rest of their lives.