Meeting of managing committee has to be called to elect new chairman 

2) send letter to secretary as to why MC has not been called to elect new chairman 

3) complain to registrar against MC 

1) You can make complaint to registrar of Cooperative Housing Society of Thane area. If your society is registered. 

2) Before that get all members meeting in the society in common forum to appoint new chairman.

The managing committee has to take a meeting and then appoint new chairman if they fail you can approach the registrar of the society.

Dear Sir,

Complaint may be made to the Deputy Registrar concerned department i.e Society's Registration Authority or approach the High Court for necessary direction.  Before that a legal notice may be issued to the Secretary.

Maharashtra Co-operative Housing Society Bye Laws

1. MANAGEMENT OF THE AFFAIRS OF THE SOCIETY

129. In the event of vacancies in the Committee, caused on account of the death, resignation, disqualification or removal of any members of the Committee, by the Registrar, the Committee may fill in such vacancies by co-option on the Committee of any other members eligible to be on the Committee, irrespective of fact whether there is the quorum or not, not withstanding anything contained in the Bye-law No. 127. However, such vacancies by co-option shall not be more than

Please immediately drop a mail to the Registrar of the Co-operative Societies giving the full details/facts, then see what happens.

You can file Complaint to deputy registrar for the same

Make a complaint to Registerar of co operative society  

Complain to registrar to dissolve the committee and schedule the election.

1. As per the information mentioned in the present query, makes it clear that due to the non active participation of the treasury, the work of the society is at lost.
2. You should write a representation to the treasury and other members about taking step to appoint a new chairman by way of conducting election or voting.
3. If the members do not act on it then you may have to approach the society act office to take appropriate steps for choosing a right person for the chairman post.

Upon resignation of her post, the other office bearers have to request her to continue as care taker till the time a new chairman is elected/appointed or they can make an alternative arrangement by calling a general body meeting to conduct election for this purpose or to appoint a  chairman as an interim relief till the election is to be held.