The correct option is C Triumphant
The word 'crestfallen' refers to being sad and disappointed.
Option A, disturbed refers to having had the normal pattern or functioning disrupted.
Option B, vainglorious refers to being excessively proud of oneself or one's achievements.
Option C, triumphant refers to having won a battle or contest.
Option D, indignant refers to feeling annoyance at what is perceived as unfair treatment.
Thus, according to the meaning, the word ' ' is the opposite of the word ' '.