498a case have been filed and the wife want to withdraw it

Due to certain heated moments in my house, I slapped my wife. She left the home and went to her paternal home. After that she lodged complaint in local police station and police had registered FIR under section 498a, 406, 507 and 34IPC. The case was filed against me , my mother and my aunt. Now my wife and myself had revealed the fact that due to heated up moment, the things have moved in such wrong direction and she want to withdraw the case. Accordingly, she approached Investigating officer and communicated him that she wants to withdraw the case. The IO has accordingly told her that she has to approach local lower court and file affidavit and come back to the IO with the avvidafit. My question is as follows: a) after she meets with the IO with the affidavit, how can the IO take further action? b) will the police demand some money out of this situation c) do we have to take bail. My jurisdication falls under South 24pgs, sonarpur thana, west bengal. Please guide me.