Appointment of auditor

First, the requirement of 5 years is mentioned in 139(2) and I assume that the company can call AGM(because it is generally called within 6 months from the end of FY).

The company can appoint the auditor (who audited for last 5 years) for 2016-17 only because -
1. As per 3rd proviso to 139(2), transitional period of 3 years is provided to comply with the requirement of 139(2) i.e. upto 31.03.2017

2. As per Rule 6(3) of Audit and Auditors Rules, the period for which the individual has held office as auditor prior to the commencement of the Act shall be taken into account for calculating the period of five consecutive years.

For 2017-18, new auditor has to be appointed.