Answer:
Despite the fact that no death should be justified, we can say that there were not sufficient reasons to kill Mercutio, instead there were reasons to kill Tybalt.
Step-by-step explanation:
Romeo's intervention in that street fight where he did not want his best friend or his relative to get hurt, caused Mercutio to be killed by Tybalt for no reason other than hatred.
While Tybalt, Juliet's cousin, after he kills Romeo's best friend, is fatally stabbed by Romeo in revenge for his previous act.
From what we can say that Tybalt's death is more justified than Mercutio's death.