It was all so unexpected, and all happening so fast. If she hadn't had any dreams to serve as a comparison, Wanda might have panicked and tried to run. But the shout in her brother's voice, coupled with the flurry of blows - they gave it away. She wasn't the only one without powers.
Her jaw dropped. Later she'd be angry with herself for not helping, for not trying to do something, but in the moment the shock was just too much.
She didn't try to use her own powers. Wanda didn't even move in to try and help until the man was down, crumpling as his knee went out from under him. At that point, there didn't seem to be much to do to help.
So she grabbed for her purse. It was something concrete that she could handle; she could scoop it up and grab for her pepper spray, just in case the bigger guy wasn't down for good. Out came the canister, and she fumbled to remove the safety latch.