I obviously don’t know her, but when I don’t know people, I like to play the odds.
When she was first approached, and she told her friend about it, I take this at face value.
It’s far more likely than her trying to set up some sort of deniability.
I think she said no.
When there were subsequent attempts made to solicit her help, I think she may have warmed up to the idea.
Here’s where I’m less confident:
Did she ultimately agree to help him with the events surrounding the murder (lookout, cleanup, etc)?
Or did he contact her after he killed Kelsey, and then ask for her help?
Either way, she knew what she was helping with.