a) The Renegade won.
The High Noon FAQ explicitly specifies:
As the text on the card states, each “ghost” is in play until the end of his turn: if the game ends during his turn,
he is considered to be in play for victory purposes. So, if the ghost was an Outlaw or a Deputy, Outlaws win because at least another player (the ghost himself) different from the Renegade is in play. If the ghost was the Renegade, he wins if after killing the Sheriff there are no other players alive, otherwise Outlaws win.
Edit: The dvgiochi.net site isn't stable. Here's a cached version of the same FAQ: http://webcache.googleusercontent.com/search?q=cache:go9uewu...