Compny threatening me of absconding

Dear sir, I recently got selected in a company X... I got offer letter on 18 th sep..... And accepted it where there was no mention that from now I am bound to work in that company.... After that at 28 th sep my manager said that today is my joining date but I didn't received any appointment letter... I received the letter the next day via email where at the end of the appointment letter it was written to acknowledge and accept it and to put my signature in it and send back my acceptance... But sir after going to the office I was asked to do things which was not told to me and my mother also got I'll.. So as I had the option of not to accept and acknowledge the appointment letter so I didn't..... And wrote to the HR and manager that I will not be able to join and accept the appointment letter... From then they are threatening me that they will file absconding case if I do not show my mothers medical documents or else to give resignation and serve 1 month notice period they will take action.... My question is that of I have not accepted the terms and conditions of the appointment letter and not signed it during joining.... Can they do such things and am I bound to provide any documents of my mother.... I am currently mentally disturbed.. Please help.