I feel like that black dressed person may be Kabir .. may be he sent Riddhima there expecting vansh to kill her...since he is not doing it, now he himself is trying to kill her while blame will be on vansh n his family 😈
here is one more theory:
may be Kabir's target was never vansh but Riddhima/Ragini...Ragini might have been a psycho serial killer...those skeletons beneath earth might actually be the murders riddhi/ragini did n vansh hid it (similar to imm1)...🤔