Sec 96

No, it is not like that. Central Government cant change any time. Its required permission from Both house of Parliaments to change law.

Further, your question is that, bcoz of this proviso, condition of 9 month and 15 month can be escaped. Then answer is no.

This provisions is talking about sub section 2, not sub section 1

[(2) Every annual general meeting shall be called during business hours, that is, between 9 a.m. and 6 p.m. on any day that is not a National Holiday and shall be held either at the registered office of the company or at some other place within the city, town or village in which the registered office of the company is situate:

⁴[Provided that annual general meeting of an unlisted company may be held at any place in India if consent is given in writing or by electronic mode by all the members in advance:

Provided further that] the Central Government may exempt any company from the provisions of this sub-section subject to such conditions as it may impose.

So relaxation is for Place of Meeting.