The correct option is C Joyous
The word 'piteous' refers to someone deserving or arousing pity.
Option A, pathetic refers to something arousing pity, especially through vulnerability or sadness.
Option B, joyous refers to being full of happiness and joy.
Option C, patient refers to a uncomplaining or tolerant attitude.
Option D, anxious refers to showing worry, nervousness or unease about something with an uncertain outcome.
Thus, according to the meaning, the word 'joyous' is the antonym of the word 'piteous'.