BB's suicide/disappearance came as a total surprise. So any other twist or plan is possible.
But I doubt Abhi is involved in BB's disappearance. At the same time, it can only be Abhi or Purab. Somebody needs to help BB recover. She's a patient and needs medical help. So just as dadi helped Pragya when she was in the hospital, somebody needs to take care of her. Won't be surprised if dadi is behind this, as unbelievable as that is.
I also doubt Pragya will stop her mission or reveal herself. I just posted on this on Ann5's post. I get this feeling this is a downright sati savitri kinda story with the idea wife stuff. No matter what she did this for her husband kinda thing. I remember one line dadi mentioned that if Abhi later finds out that she did all this for him his love for her will increase. I don't know on which planet, but that's a very old fashioned theme.
Or Abhi may independently find out she's fuggy and go along with her as mugambo. This is going to be a long track.