General antonyms:
* Calm
* Peace
* Quiet
* Tranquility
* Stillness
* Serene
* Order
* Harmony
More specific antonyms:
* Silence (if the commotion is noisy)
* Stillness (if the commotion is about movement)
* Calm (if the commotion is about excitement)
* Order (if the commotion is about chaos)
The best antonym will depend on the specific situation and what aspect of "commotion" you want to contrast.