When you get a parse error it means that there is a syntax error somewhere (in your case: in the config.php). It has nothing to do with whether your paths are wrong or right.
Line 90 in the original config.php is the one just after the $_CONF['site_admin_url'], so chances are you forgot a single quote or a semicolon there.
Can any one tell me how to do this URL as per above true path, properly please.
Okay, let's try it another way: When you drop a simple HTML file, say "hello.html", into your httpdocs directory, then you can call it up by entering "http://yourdomain/hello.html" in your browser, right? If so, then you should have Geeklog's index.php, lib-common.php, etc., as well as the admin directory inside your httpdocs. Then http://yourdomain/admin/moderation.php would be the correct URL to the Admin's moderation page. Which means that the default setting for $_CONF['site_admin_url'], which I already quoted above, would be the correct choice for your site.
Also, I just realised you seem to have the config.php inside the httpdocs directory. It shouldn't be there, as that means it's accessible from a URL - and you really don't want that.
config.php, the system directory, and everything else that was
not in Geeklog's public_html should be outside of your httpdocs directory, i.e. in /home/httpd/vhosts/domain.com
Or, to put it another way: Imagine that "public_html" was really named "httpdocs". So everything that's inside "public_html" should go inside your httpdocs directory (keeping all the folders), and what's outside of public_html should also be outside of httpdocs on your server.
Hope that helps (and yes, I know: "By making something absolutely clear, somebody will be confused" ...).
bye, Dirk