I go to my in laws on rare occasions for this reason. It took may years and MIL has stopped inviting her friends over on shabbos and YT when we do come. it was a group effort of the married kids to explain so she can understand that we have no interest in spending shabbos/YT with her friends.
I usually let her do what she wants and if I disapporve I tell my kids that they cant and tell my MIL things like “please dont give the kids lollies or other sugar filled junk @ 9.00pm” She used to give me a blank look but she come a long way and understands that she has to respect our way of rasing kids.
Show her that you are in charge of your family. it may work