Each goddess in this clique is married to somebody important. Power players, movers, and the who's who of the gods all meet with Mut in this interesting, oh-so-charming group.
When people think Odin's got all the power in Asgard, they need to stop and think again. Frigg, Odin's wife, is incredibly powerful on her own. Norse myth says she knows everything that will ever happen, but chooses not to speak of it. Living with a guy who gave up an eye for knowledge? Not talking about the things she knows that Odin doesn't has to take some guts.
Hera would be powerful in Olympus even if she weren't married to Zeus. (She's also a lot less of an unpredictable jerk.) She's the queen of the gods, and her superpower seems to be turning various women into animals and inanimate objects. Of course they all deserve it. (Are you going to tell her she's just taking her rage at Zeus out on the poor girls?)
Isis is still married to Osiris, but since he's dead, she gets to run the family business and everything else on her own. Mut and Isis spend so much time together that the Greeks and Romans have a habit of mistaking them for each other.