You can try to make a safe squishy space for someone to be a little messy & a little difficult for a while, but it's impossible to build a wall around someone high enough to block out all their insecurities.
There is nothing that other people could do that would make it so she never felt left out of something. There will always be a joke she doesn't get or a movie she doesn't enjoy. Or just a suspected feeling that maybe other people are connecting more closely with others than with her.