The assassin who shoots the guest at the funeral could be an antihero, as the audience does not know whether the guest is being shot for a valid reason or not. However, the hero is not known at this stage in the story line as it is not revealed what has happened previously which is then shown in the film.
Scenario 2
It is hard to distinguish which part in the film this character plays or whether it is a MacGuffin and is leading us in the wrong direction. It starts the audience guessing but it is most likely that they will assume that the man in the womans bedroom is the antagonist, however this may not be true as this early in the story we do not know anything about any of the characters.