Honestly, I thought she was just seeing things. Her life was ending, and she wanted so badly to see Chrno one last time that she did
, but not because he was actually there. I pretty much got the impression that, compared to her time with Chrno, everything else in her life paled. I thought his appearance, right at the end, was a way to show that...she wanted to see him so badly that she imagined it. Alternatively, do they ever show anyone finding her body? While reading it another thought I had was that she could have died sitting right in that pew, and everything after that, walking toward the church exit (into the light...>__>) and Chrno was her moving on (her spirit moving on, I guess). Or she did make it down that aisle, and the part about Chrno being there was a figment of her imagination: there could have been no one, or it could have been someone else entirely, and she just saw
them as Chrno because that's who she wanted it to be. She did
know she was dying, I remember her giving herself a pep-talk of sorts.