He felt tired with the monotony of his daily routine.

Answer: Option B

Monotony : lack of variety and interest; tedious repetition and routine.
Peacefulness : state of calm or tranquility.
Variety : the quality or state of being different or diverse; the absence of uniformity or monotony.
Excitement : a feeling of great enthusiasm and eagerness.
Range : the area of variation between upper and lower limits on a particular scale.

Antonym of Monotony is Variety