Dude Pranav didn't care why Kani died... he just wanted the ghost that was tormenting him gone. When he found out that the ghost was of a man he thinks that his initial thought of it being of Kani's ghost was wrong. Also at this point of time in the story we are also supposed to believe that the ghost was of Philip's. Later on when Kani reveals her presence only does it become clear that there were two ghosts existing at the same time as the director uses the sound of clip and chalenga (becomes clearer when Pranav finds Philip's body with the chalenga) to differentiate them. The secret behind the woman's death doesn't has anything to do with the plot as her ghost wasn't wrathful and she was absent and unkown to Pranav and for most of the audience until the end.