Captain Thalo'thas Brightsun wants Fairmount killed.
As of the Cataclysm, Fairmount is no where to be found. It is possible she was killed by Horde adventurers. It's odd to note however, unlike the other named NPCs in the quest to kill her, she is the only one that does not reappear, the others showing up alive and well. It is possible she is either away or was killed in the initial assault on Northwatch.