I will be 111. I hope i never see it.
The lucky ones that are within 100 miles of the impact zone will be evaporated in 1 millionth of a second. faster the a nervous system can register. The unlucky ones will be burned, or frozen in a nuclear type winter or starve to death.
Attaching a small solar sail to the comet can and will toss it off course even if you put the sail behind it and let the tail burn inside it that would generate a rocket effect and push the comet. I say let mars eat the bitch and then watch the show from the front row this time.