From the current OLVs and AdiZa's IV, I'm really starting to think that this wedding/fire plan is a joint effort by both Avni and Neil! There was a picture I saw on YouTube ( I don't have the link!) that showed Avni sitting in the car with Mishti, after the fire, and she's giving a thumbs up to someone. My guess is that someone is Neil!
We saw from the OLVs that Neil was holding vidyut as he cried and vidyut's attention was diverted, so maybe that was the plan the allow Avni to run away,without being seen! And that's why we get the ghost scenes later on! Because vidyut actually believes she's died.
This is ONLY a theory of mine! I wasn't going to speculate but there's a lot of rumours floating around and I thought I should share something positive!