I think Rantej stabbed her. And Yuvraj is trying to shield him.
And deep in my heart I feel Ammaji did not kill Yuvraj's parents. Balwant created a drama in front of his eyes to blame Ammaji. Actually Balwant got his parents killed.
This may be my fertile imagination because I am biased towards Yuvraj and Ammaji 😊 but It would be nice to know other members POV.