mob outfit for casual beach wedding

So, my mother has no idea what to wear to my wedding and I honestly don’t know what to tell her. My website lists dress code as beach casual-be comfortable. I’m picturing cute sun dresses for the women and maybe khakis and a fun print shirt for the guys. But how does that translate to MOB (or MOG)? Just a nice casual dress? Traditional MOB dresses are obviously too dressy for our wedding.
My mother hasn’t asked yet but I know it’s coming. FMIL, meanwhile, may not particularly care what the dress code is (another post for another day).