After meeting the holy man, his nagging mood of diffidence suddenly changed.

Answer: Option B

Diffidence : modesty or shyness resulting from a lack of self-confidence.
Confusion : uncertainty about what is happening, intended, or required.
Self-assurance : confidence in one's own abilities or character.
Contentment : a state of happiness and satisfaction.
Consternation : a feeling of anxiety or dismay, typically at something unexpected.

Antonym of Diffidence is Self-assurance