Is The Server Running Locally And Accepting

This kind of error happens when PostgreSQL server does not run due to force shut down because if you delete a postmaster. Pid without crosschecking if any process is running this could permanently corrupt your database.

And if this happens then you can use the procedure:

1. Uninstall the PostgreSQL using Brew
2. Remove all the PostgreSQL folders
3. Then again reinstall the PostgreSQL using Brew
4. start server using the command: 

Brew services start PostgreSQL

Now you can create your database.