What was she... *SPOILERS*

I couldn't really figure out the ending myself. My guess was that the MySon drug was mass marketed somehow. So when the mother says, I'll go to the West that's the only place untouched. She must mean she's taking some sort of MySon antidote or vaccine with her, that I guess can work through the air.

It's hard to say. The ending really was open-ended. I read the director has a penchant for apocalyptic themed films though, so it works in that sense at least.

I thought maybe she had gained the knowledge of how to make the Myson drug when she was connected to Eiji through that weird VR thing. And since she turned out to be psycho, I figured she was spreading the Myson through the populated areas, 'cause she was sick like that. That's why she said she was going west, since it hadn't been contaminated yet, and she wanted it contaminated.