I would help her. I cannot let anyone die by me; even if I must loose my own life in the process. Also; if she was a serial killer most likely not be crossingthe road where everyone can see her. I would of course see if shes limping or holding an injuryor something like that, then check her for weapons. A lot of girls like that sort of person, and would like to help anyway possible, anyway.... Not really though; I wouldn't take advantage.
discussion

...i know how to rebut that too,
WHAT IF ITS NOT HER BLOOD HUH!?!?!?!?!?! WHAT IF SHE IS A KILLER AND WHEN YOU STOP SHES GONNA PULL OUT A CHAINSAW AND KILL YOU!!!???
First you do B, then A. Problem solved!