They are likely just there to visit with friends. Brie and Nikki announced their retirement from WWE a few months ago on Total Bellas.
Bray Wyatt is also backstage at Raw. No word on if he will actually appear on the show. He could be there to film some pre-tapes but, as previously noted, it is interesting that they flew him to Los Angeles from Orlando. We’ll see if he actually appears tonight on the show.