TURN OVER APPLICABLE 9 and 9C

Yes section of GST Audit is applicable.

For the year 2017-18, turnover shall be taken from July to March.
hence no requirement of 9C.
however it is advisable to file GSTR-9

OPTIONAL FOR GSTR9

Wording used in the section 35(5) "Every registered person whose turnover during a financial year exceeds the prescribed limit". Thus tournover of whole FY is taken in to account for applicability of GST Audit. However For the purpose of finding out the turnover limit for Financial Year 2017-18, it has been clarified in the government’s press release dated 3 July 2019. It shall cover the period 1 July 2017 to 31 March 2018 and excludes the first quarter of FY 2017-18.

So its not Applicable bcz of bellow 2cr sir

Yes not applicable.
However it is advisable to file GSTR-9