If you have trouble with the upgrade, use this link; http://www.mozilla.org/en-US/firefox/all/

Separate Security Issue: Update your Flash Player or remove it.

Suresh_Babu said

not able to update firefox

You appear to the a Ubuntu package build of Firefox 52.

Check for updates for Firefox in your package manager.

Or you can use the tarbal from www.mozilla.org/firefox/all/

Just make sure the firefox folder has read/write permissions so it can get updates. A easy way if you are the only user is to have Firefox in /Home/username/folder

You also appear to still have a old Flash 11.2.x version when Adobe has supported Linux with current branches of Flash ever since mid-December 2016.