i think its ranbir... not trying to kill milind but trying to keep an eye on him so that he can catch someone who is wandering around milind... otherwise why would ranbir throwy a party and plan to kill milind at his own party thats just stupid.
and i realized that some people are getting suspecious abt the things he said. but i think when she said whatever is yours is mine, he meant somuya... probably and family... cuz he said he didnt have a loving family like milind's so yeah...
but yeah you never know, there is possiblity that ranbir can the killer but as of now, i dont think they have given us any hint that Ranbir could be the killer. who knows maybe its as simple as they show it, that neev is the killer... because he is gonna leave the show they need to show him negative so the people dont cry over him leaving the show.