Peaches, check your dad's paperwork and see if he got disability insurance on his lease!!! Many people forget or don't really know what they bought, so maybe he go it. If he did, you and your mom don't have to worry about the payments until he's either better (sorry to hear about the illness, I know it's a tough road) or the lease ends.
So many people think the insurance is not worth it, but they haven't seen the tears of joy of my customers when their loan is paid out in time of need.