Whom are the witches preparing to meet in scene 3 of macbeth?

He who is not to be named or in other words Macbeth

Hope this helped you ;)

Anna:- Oh my gosh! These dinosaur bones are absolutely spectacular.
Stephanie:- I’ve been waiting to come here for so long. This is amazing! Look over there, it’s the fossilized eggs of a Tyrannosaurus rex.
Anna:- Let’s go closer.
Stephanie:- Not too close. We don’t want to hatch and think we are the parents!
Anna:- That’s not even possible, Stephanie.
Stephanie:- Are you sure? I’m a bit skeptical.
Anna:- Yes, I’m very sure.
Stephanie:- ...well, if you say so. But if it hatches, I’m blaming it on you!

I hope that helps.