Mom/friend drama

Ok so i (girl 22) need advice…a lil backstory my mom has had a leg injury for the past 9 months so she has had a rough few months physically but most of all mentally…i’ve been there for her and fortunately she has a group of friends she has had since i was a kid and they’re all in a painting class. Anyways, they have planning a trip to mexico since may? idk but originally my mom didn’t wanna go because of her leg but they all convinced her to go specially one of her best friends, let’s call her Annie. So annie has been friends with my mom a really long time and you know the drill..they have dinners, and bbqs and they’re really good friends and they have been to other trips together just not in another country. But ever since they started planning the trip the entire friend group has been really….annoying lol. Like they started giving my shit bc she was going to leave earlier than them and didn’t want to go to some of the activities that they wanted to do but my mom doesn’t really care but her “best friend” is always throwing comments. Like how the best part of the trip if going to be Puebla which is after my mom if gone…now my mom planned another trip right before theirs with my dad to cdmx to watch some concerts but she planned so she could still go on the plane with the group and the “friends” were like omgg you should’ve just stayed omg. And now my mom is feeling really bad and doesn’t even want to go. And i’m really protective of her so i really want to call up the “best friend” and just talk and say that she shouldn’t treat my mom like after everything that she has done for her. but idk i just don’t want my mom to be treated like that in the trip especially if im not there to defend her. And i feel like i do have that relationship with the “best friend” to call her or at least text her and say something..but im conflicted i don’t want to cause unnecessary drama