After watching Bhabo in yesterday's episode, some how, I don't feel that she is guilty of killing her son. So may be he died only after she left the place and in her presence he was very much alive. So when Suraj saw BB hitting Mohit and him falling on the cart, Suraj would have urged BB to leave the place and he would have accompanied her till the road side and by the time he returned back to the spot, he would have found Mohit dead. So he has presumed that death happened because of the blow BB given to Mohit and so he is trying to save her.
Meanwhile some one else would have reached the spot and completed the task.
That explains why Bhabo is asking Sandya to take good care of her husband and never to leave him alone and vice versa. She also advised Suraj to never stop supporting Sandya. If she were guilty, she would not have agreed to go for operation, leaving Suraj to face the music. She may not even have the slightest inclination about Suraj suspecting BB killed Mohit.
So only when she comes to know aboutb Suarj taking the blame of killing Mohit, it would have striked her that her son was trying hard to save her thinking she killed him or even she may be thinking of saving Suraj by taking the blame on hersef.
So what made Suraj dump the body to the well, if he was going to call the police and alert them about the dead body?