The fundamental question is; have you bought that open space or is owned by you. Now the society wanted to build a community Hall on an open space which doesn't belong to you. For me you are unnecessary taking 'panga' with the society. Please avoid it.
What do you mean by society? Is it registered society of the residents or in Hindi which meant समाज? If it is registered society of the residents then talk to them and resolve the problem amicably because you will be residing there all of your life. What else you alone could do?