First of all, I am so sorry for your loss!! My heart and thoughts are with you and your mom!!
Second of all, is there ANY chance that your parents had "survivor insurance" rolled into the loan? I don't think I have the name of the insurance correct, BTW, so don't ask about it using that term exactly.
In essence, its insurance that relieves the surviving spouse of paying the balance of the loan in the event of one of the account/loan holder's death. We've had that on the past three car loans we've had ... and I am fair sure it's rather common.
How that would be affected by repossession and how much time has passed SONCE the repo, I don't know. I'll Google this evening and see what I can see -- unless someone else chimes in sooner with more info as to whether or not its a mitigating factor.
Again, my heart goes out to you and your dear mom!!