Another great episode. First time I ever felt rooting for Tsuruko. Also keep fighting Anaru!!!
Anyway, this is my theory, I think that Menma will only be able to go to heaven when Jinta finally learns to let go. I think the whole appearance of Menma and why he's the only one that can see her is because of his deep feelings of attachment, regret and resentment. The strong negative and unhealthy emotions that have festered in him over the years cause this phenomenon, and Menma is there to help "fix" Jinta.
I'll be damn if I'm right
Edit: I think it'll be funny if Menma reincarnates as Jinta and Anjou's daughter