Hannibal got a bit away when he stopped because - damnit. He didn't have a heroic bone in his body, he hunted vampires because of revenge more so then out of some desire to save people. But he couldn't let some monster just run around, maybe it bit people and they turned into mini monsters. Yeah, he'd go with that justification to explain why he turned around and ran back.
The woman (who had shurnk down to a smaller version - wasn't she one of those Avengers?) seem to blast at the thing, it didn't seem to work so Hannibal got out his gun and fired a shot. That seemed to piss it off as well, but now it was trying to decide who it wanted to swat more, him or her.