His diabolical ways made him unpopular.

Answer: Option C

Diabolical : characteristic of the Devil, or so evil as to be suggestive of the Devil.
Mischievous : causing or showing a fondness for causing trouble in a playful way.
Lavish : sumptuously rich, elaborate, or luxurious.
Seraphic : characteristic of or resembling a seraph or seraphim; angelic.
Azure : bright blue in colour like a cloudless sky.

Antonym of Diabolical is Seraphic