Thawne Calls Nora "Dawn". Why? Probably because, in the timeline he remembers (where Nora Allen wasn't killed), Barry named his daughter Dawn. Nora is only named after Barry's mom because Thawne went back in time and killed her, thus creating the show's main timeline. Thawne also mentions "at least you still have one," alluding to the fact that Dawn was a twin in the comics.