I thought he was referring to Dylan also. There is a small inconsistency though. When Caleb was visiting Dylan, Dylan told Caleb that he doesn't talk to Norma or Norman anymore. So Dylan wouldn't have known if his mother died anyways.

There's something I don't understand. Norman was standing in front of the guy who was hired by Romero to kill him, so how did the Norma personality part of Norman (who Norman doesn't know is actually himself) kill that guy from behind?