Considering the implication if she's able to join the Gehenna meeting, I think it means she's with Mephisto plan the whole time.
We already saw her sit on the same side of the table as Amaimon and Belzebub in chapter 86. So it's safe to say she was on Mephisto's side this whole time.
Also does that mean Armumahael and Azazel's nephilim can also enter baal? Wonder why they were not in the meeting with Satan where the rest of the baal and Shemihaza's nephilim were.
We have almost zero information about the other two Grigori so nothing can be said to them yet. (The Azazel representative probably doesn't really have the authority to make decision, then the remaining question is how the Shemihaza department interact with Armumahel department.)
I don't know or remember about the representative of Armumael, but concerning Azazel's representative, if I remember correctly, he's not Azazel's descendant and, as far as we know, he's not even the descendant of any other demon, so he may very well be 100% human. I don't know if humans can go to Gehena, but I guess it's not a place where he wants to be...
I just realised... Maybe Shirou isn't dead. He stabbed himself in the heart, but now we know he can survive that. And then he was taken by the Gehena gate, but now we know it's a place where people can live and have at least some sort of form in space and time...