See if you have not taken plan approvals and there is no permission and conversion to commercial property they can seize and can order demolition of the property. You have to apply for taking necessary permission though plans cannot be approved now. Further you can also reach out and try before high court if there is such order. 

You can file a writ petition immediately before high court for appropriate direction

you need to register under Shops and Establishment Act of your state. 

Obtain permission from muncipal corporation to use premises as banquet hall 

Pay regularisation charges imposed by muncipal corporation 

You cannot run the commercial activity from your residence and in case you are doing this you have to take permission from  respective authorities this regard you need to regularise the property as commercial property after payment of the penalties and any levy imposed by the Nagar Nigam in this regard and your electrical connection is commercial electric connection

Dear,

        Without proper permission, you can,t run activity like this in residential or any are.

        You have to take proper permission from municipal corporation.

        and you have to pay fine for you did earlier.

         After permission you can do anything.

        After this if they are not giving you permission, you can file writ for proper direction in high court. 

At any time the Development Auth. passes an order against you, sealing your premises or otherwise restraining you from operating this banquet hall and lawn, you will have the remedy to approach the Allahabad High Court and file a writ petition. 

apply for permission for running banquet hall in the premises 

You can do the aforesaid

Hospital comes under necessity, well, no big deal, you are operating Banquet hall and lawn for commercial purpose without license, it will unseal by payign penalty. 

And if no event organized yet than no sealing, you can use your residential property for personal use by your choice.

See for banquet hall plan approval and conversion to commercial property is required. Tax has to be paid as per same. 

It is illegal on your part to convert the residential accommodation to a commercial banquet hall.

Since you have received the notice you may issue a reply stating that it is not a commercial establishment but only for own use however you are ready to pay the penalty  and bring it back to the originally approved plan.

If your reply is satisfactory then the authorities may let it off with penalty and a warning  to not to indulge in such a thing in future, you may consult an advocate in the local and proceed on the further advise received.

Since you have not obtained permission from the competent authorities to convert the residential place to commercial complex, you have lost the ground to defend your interest.

You may take the assistance of an advocate and try to minimise the penalty in this regard and get the seal broken.