To Defend Ezequiel basically grab his head and pull it towards you.
To choke you he need after secure the grip and push the hand into your neck and to have the leverage to do that he need to get space .
Its more effective as defense if when you hug his head, his choking arm is inside your grip too.
Basically is like you get a Head and arm controll (like when you do on top of side mount) but from the bottom, with also the choking forearm inside this grip.
Same if he do the Ezequiel from the back (Like Rodolfo Viera Do), just try to turn and grab his head and pull the head as close to you as possible.
He cannot choke then.