GST Registration for WFH Freelancers

I myself filled for a GST Registration mentioning my residential address as principal place of business.  (Note i have provided NOC as well).

Now I got a show cause notice asking to show the Business name board at principal place of business.   

Would like to know Is this mandatory to show the business name board at our residential place?

And also afraid to stick name board at my residence suspecting may increase the Electricity and water rate. 

Your valuable suggestion on this is highly appreciated.

Thanks

Anu