School loans and federal taxes; does this loan now fall to my mother?

Hi! My stepdad recently passed, he was younger than my mother. Several years after he finished his classes he became disabled, he tried to work. Long story... I had no idea how bad their financial situation was. He had stopped paying the life insurance before he passed and wasn’t old enough to get retirement benefits. Due to this my mom who has already had several strokes and just had another one is not getting any benefits, except her own from retirement. I found his school loans and the amount due is over $180,000 left. He was past due on the payments. The letter stated they could take any taxes owed to him. Since he was married does that mean that this loan now falls to my mother? These school loans were regular school loans. Thanks for any help.