Gosh we have a lot of Mother -Mother in Law--issues here!I am glad you are sharing them because I look at it in a positive way--I learn more and more of what I need to change about myself.
I understand why you would want his family to know your son as it is the only family he has. But then again if this gets out of hand--it might be better to have you son see less of them.
They have that ole time Irish Catholic disease---same one I have and half my family. Drinking was a way of life=a passage for a young man-and not taken seriously-almost expected. Things have changed dramatically as the generations change.
Knowledge is the key as it is with everything .
She is old -as you say- I would never argue or talk back--just let it go. But you don't have to take it from the A!!!