The principle says killing is not murder if it happens in a sudden fight, without premeditation, in the heat of passion, upon a sudden quarrel. X and Y quarrelled at 7 pm while buying liquor, X threatened Y, Y dared him to come to his house nearby, and X then went back to his own shop, got a knife, and went to Y's house two hours later at 9 pm to stab him.
Because X had time to cool off, chose to arm himself, and travelled to Y's house before the killing, the facts show premeditation rather than a sudden, unplanned fight, so the exception in the principle does not apply.
Therefore, the correct answer is X has committed murder.
The fact that decides this question is the two hour gap between the 7 pm quarrel and the 9 pm stabbing, during which X walked away, fetched a knife, and travelled to Y's house. The principle's exception depends on suddenness, so each option can be tested against whether that gap and preparation are consistent with a sudden, unplanned fight.
Testing each option against the two hour gap and the deliberate arming, rather than against enmity or the fact of the killing itself, leaves only the option finding murder.
Therefore, the correct answer is X has committed murder.