As-3 applicability

Yes it is mandatory... below is the text from Accounting standard 3 about the applicability. And the marked portion is the parameter which mandates the preparation of cash flow statement in your mentioned scenario.

This Standard is mandatory in
nature2 in respect of accounting periods commencing on or after 1-4-20043 for
the enterprises which fall in any one or more of the following categories, at
any time during the accounting period:

(i) Enterprises whose equity or debt securities are listed whether in
India or outside India.

 

(ii) Enterprises which are in the process of listing their equity or
debt securities as evidenced by the board of directors’ resolution
in this regard.
(iii) Banks including co-operative banks.
(iv) Financial institutions.
(v) Enterprises carrying on insurance business.
(vi) All commercial, industrial and business reporting enterprises,
whose turnover for the immediately preceding accounting period
on the basis of audited financial statements exceeds Rs. 50 crore.
Turnover does not include ‘other income’.
(vii) All commercial, industrial and business reporting enterprises
having borrowings, including public deposits, in excess of Rs.
10 crore at any time during the accounting period.
(viii)Holding and subsidiary enterprises of any one of the above at
any time during the accounting period.

Not applicable because turnover is less than 50 Cr. but if enterprises fall under any of above the reporting will mandatory.