Guys this is a spoilet based on one huge article i read here in Gujarati Newspaper and it was great marketing strategy as if some real crime article.
Here is the reason.
Vansh knows that Ragini saw killers of Uma (Vansh Real Mom) and that killer harmed her and she went in coma.
So Vansh had kept Ragini in that factory so that when she wakes up from coma he can get to know from her that who killed his Mother.
This means Ridhima made a huge blunder this time by her act and allowed Kabir to influence her in escaping with Ragini.
I feel Ragini must have seen either Kabir or who knows Sia killing Uma Raisinghania