As Arsalan said, ossndata must be in a directory that is NOT visible to the web. This means if your site root (http://mysite.com) is in htdocs/mysite.com/, your ossndata directory should be htdocs/ossndata. If you want to put ossndata somewhere else, you can set a different directory in ossn.config.site.php. Try putting ossndata in a directory that's not viewable to the web, make sure your config file reflects that change, and for good measure you might want to try a chmod -R 777 ossndata to make sure you don't have any issues with permissions.

Thanks for the Reply, Here is the Issues, My site is running on /mysite.com/htdocs/ossn_data files/ thats the directory having the issues, and if I tried unzipping ossn files in folder eg /mysite.com/htdocs/ossn with file inside, the website link will go through mysite.com/ossn_data not mysite.com after the installation, and through mysite.com/ossn everything is working perfectly well including cache and Components being installed without any problems i wonder what exactly am doing wrong here.

Check that your Ossn installation has the correct owner and access rights.
You can use the verifyperms.php tool to investigate. See
https://www.opensource-socialnetwork.org/component/view/1963/system-info

If your website is inhtdocs/mywebsite.com/ your ossn_data directory should be in htdocs/ossn_data/

For some reasons your ossn_data directory must not be inside public directory or htdocs.