From the Official Brady Strategy Guide for World of Warcraft, released November 2004

https://archive.org/details/World_of_Warcraft_World_of_Warcraft_BradyGames_Official_Strategy_Guide/page/n35/mode/2up

"VC Van Cleef - Boss of Deadmines instance in Westfall. Sometimes used interchangeably with 'Deadmines.' (ie. LFG VC is the same as LFG Deadmines.)"
Page 9.

The VC initials literally come from the fucking beta of the game, predating the official launch.