Login to your 000webhost.com account
Hit Settings then Security on the menu
Browse down to "Manage IP addresses"
Click on add
Fill in the box with the IP address you wish to deny from your site
I got the IP address from my analytics script to block an abusive commenting user for example.
Now the visitor using that IP will not be able to load my site until they change their IP.
The visitor will see no message informing them of the blocking either.