Your mother in law needs friends of her own age, she's going to be uncomfortable amongst your friends as they're from a different generation, possibly backgrounds and what she would consider rude they consider as normal as you are all so close, you don't necessarily stick to social niceties (I know my friends and I don't).
Can you invite a few of your friends around to yours at a time with their mothers in law/mothers etc and encourage them to interact?
Btw, don't tell your friends your mother in law has taken acception to them and their offspring it will cause unneccessary bad feeling, and then tell your mother in law you haven't said anything either just to clear the air....unless you have in which case I have no idea on that one.
Try and maintain a respect for your mother in law, ensure she has her own space, it's hard having a third person living with you I know we had our grandmother living with us from when I was 11 years old.
Lots of duas for you all inshallah.