Something I'm confused about

At the beginning, when the brother was on the ground, and the doctor went over to see about the woman, I thought at first that she was his sister (or wife or gf, since I didn't know what the woman was to him) because when he stood up and started walking, he screamed, "No!" So I thought that woman was with him, and she was dead, or he thought she was dead. Then it goes straight to his sister, and her at the hospital being upset and trying to kill that woman. So if it wasn't someone with him, why did he yell "NO!"?

And the description said she was trying to get revenge on anyone involved, but I didn't see how some of the ones she killed were involved in any way. Plus, what the heck did she think the doctor could have done that he didn't? Well, I guess the answer to that was she was a psycho freak. But some of these LMN movies are worse than others, and I think this is one of the worst ones.

Fiction is a lie, and good fiction is the truth inside the lie.--Stephen King