Gstr 9c for Exempt sale

Every registered taxable person whose turnover during a financial year exceeds the prescribed limit [as per the latest GST Rules, the turnover limit is above Rs 2 crore^] shall get his accounts audited by a chartered accountant or a cost accountant.
^For businesses with an annual turnover of less than Rs 5 crore, filing of GSTR-9C for FY 2018-19 has been waived off.
So, For F.Y 2017-18 GSTR 9C limit is 2 Crore
For F.Y 2018-19 it's 5 Crores

Note: Exempt sale also considered for calculation of total turnover..

As per Notification No. 16/2020 - Central Tax, dated 23rd March 2020, Filing of Reconciliation Statement and Audit Report ( FORM GSTR-9C ) for FY 2018-19 has been made "MANDATORY" only for those persons whose Aggregate Turnover "Exceeds Rs. 5 crores." A new Proviso was inserted to Rule 80(3) of the CGST Rules 2017 specifically for the Financial Year 2018-19.

So you are not required to file GSTR-9C for FY 2018-19.