I'm not sure if it's quacking in this case. I think his mother and your mother are voicing their real feelings about all this. She may have bailed him out, but we do not know if this was easy or if it's killing her too. I will say that leaving my son to sit in jail is a whole different situation than leaving my husband there. His mother may be heartbroken and she may have no education or support to guide her.
It sounds like your mother is just fed up.
Each person involved comes to it from theri own place. I feel a great deal of heart to each. A mother worried about her son, a mother worried about her daughter.
I think it's important to evaluate if what you are doing in your own recovery is actually effective.