Regarding false charge u/s 420 406 467

respected experts my grandfather takes me to a bank for transferring 7laks rs to my mother acc from his acc which he has to pay in return for a part of gold (total 80sovereign) that my mother gave it to him to keep in his custody from 2007. when my mother asked the remaining gold, he refused to return back and went to bank after 12days and falsely alleged that the amount was erroneously credited to unknown acc and retransferred to his acc. then my mother approached bank and by stating the situation got our money back. then comes his criminal mind he approached police station stating he asked his grandson(me) to write Challan for transferring amount from his account to her wife acc and instead his grandson(me) wrote his mother acc number and transferred the amount. the police after full investigation from bank dropped the case. then now he approached honorable court and made a direction to file FIR. then the case got transferred to another station and by influencing police , fIR was registered against me mother father sister . we applied for AB. now he s demanding to sign a document agreeing that my mother has got all 80sovereign of gold and not to file any case against him. we got AB now . please help me how to move further ? both my mother and sister are govt servant. myself medical student. somehow by stating my sister influenced bankofficers but she s working in another bank.kindly help how to proceed further