Yeah that strategy is awesome!Goo chapter but kinda short. Mavis truly beat him at his own game.
He was talking about Mavis I am sure.Zeira had also grown, just like Mavis. If Hiro wanted to emphasize she was a ghost or something, her having changed, Yuriy being able to see her (and Zeira herself trying to hide) but above all Yuriy's reaction on the last page is very peculiar. He acts like something is going to happen to Zeira, which is already odd if she's a ghost, but he even said he felt some kind of attraction to her.
So yea I'm shipping Zeira as Makarov's mom.