Using the information provided, I believe that you need the following:
RewriteCond %{REMOTE_ADDR} ^your_ip$
RewriteRule (.*)/$ $1/index.php
RewriteCond %{REMOTE_ADDR} !^your_ip$
RewriteRule index.php$ index.html
, IP- index.php, index.html
, :
DirectoryIndex index.html
RewriteCond %{REMOTE_ADDR} ^your\.ip\.000\.000$
RewriteRule ^index.html$ index.php