From what I get it, the fantasy/hallucination wss made by Batel for herself and Pike, because she knew they would never see again andshe (somehow, I guess that's part of the Beholder superpower?) constructed a fake world so they could, in some way, live their life together. That's why Pike didn't suffer the accident, and that's why Bayel thanks him on her deathbed and tells him to open the door. She got her life together with him, it was time to get back to reality and become the Guardian.

That's also why the falling star happears in the planet, she told him she would follow everywhere in his heart, and a falling star happears ("here I am" she says in the fantasy life).