If she was the cosigner, they should have been contacting him well before it made it to collections
Wow, I think the dbf is sugar coating things. I think he thought when he did not come up with funds Grandma would, then she passed away. I don't know what kind of student loan needed a cosigner, as a student over 18 I signed my own papers w/o credit or cosigner.
I would not entangle your life legally into his with this mess. It could mean the rest of his life of income tax returns being garnished, wages, even if they reduce it, they won't forgive it.
He would have been the first contact within months of graduation. If he had mail sent to grandma, was she even in financial means of making his parents and why would she if she did have funds?
There are more questions then just he is freaking out what can he do.
Think again about hooking your wagon to this horses behind. If he were my own son I would tell you the same thing.
I had a $1,200 student loan before I got married. Graduated the week after the first baby was born. the ex left soon after. I had $200 in welfare and he was $thousands in arrears on child support. I tried to send $40 a month, then months as winter I did not have it. After the ex finally paid up and welfare took the money I tried to get enough work, 2 pt jobs. The nasty contacts came, I was only paying near enough for interest. I filed income tax and only had earned income credit for the nominal hrs I worked...
the Earn income credit of $500 was taken by the DOE for the payments and balance of interest owed. For awhile that was all I could do, send toward interest, and they took the income tax returns. I knew I had to pay it off before I remarried, so I finally found a full time job, and fiancee stayed with the kids while I worked a second pt job doing security work. I paid it off before the wedding. my now dh wanted to pay it off, but I would not allow him.
Long story ends.... by the time the $1,200 loan was paid off, it was $3,800. Yes it took me from 1982, until 1990.