The old lady in the begginning theory
So it's pretty much confirmed.
In the gantz movie Reika had a black ball after escaping the room, and was in a mission to kill these people the black ball told her to kill.
She was a recruiter (sounds familiar?) that's right. Nishi wasn't lying and he somehow knew.
Somehow that old lady had 100 points and escaped the room, Only to get a black ball and was given a mission to kill Kurono.
After her attempt by talking to her, She has already founded out that he has been killed.
She even possibly pushed the hobo down and knew Kei would help out, As to why she was kindly asking for directions, her thinking he would kindly help, but was found to be confused and shocked.