One who is determined to exact full vengeance for wrongs done to him

Answer: Option C

One word substitute is Vindictive.

Vindicator: a person who clears someone of blame or suspicion.
Usurer: a person who lends money at unreasonably high rates of interest.
Vindictive: having or showing a strong or unreasoning desire for revenge.
Virulent: (of a disease or poison) extremely severe or harmful in its effects.