Is NOC required before giving my flat on leave and license

My mother is a single parent and has been giving her flat on rent from several years but now when the committee has changed there is a rule passed for NOC by the new secretary who gives his flat on rent commercially but never submitted the noc till now which I know and even the treasurer who is using his power with him has also given his flat after buying it initially this year but has imposed the rule for my mothers flat where they can see we aren't a tough competition for them and even have made the building into repair where the share per flat is too much that my mother cannot pay it in one go as our bread and butter is from that rent money so we asked them that we will pay it in instalments in 4-5 years only when our flat goes on rent but they are forcing us to pay full payment under months as other have done but the per flat share is more than the whole year flat rent so we also requested them but they are creating trouble for us and just after my mothers flat went on rent and gave them the first instalment for the year they refused to take it and threating us to complaint in the police department and removing the tenant from the house for not taking society NOC where we are telling them that when the house goes on rent only then and that to from months that we can only pay as the flat goes on rent and in years instalment as i mentioned above plus want us to pay the whole repair share and then give it on rent,now what should I and my mother do as they are financially superior plus we don't have any law knowledge plz help.