The latest version of firefox does not have firebug, how can i use firebug even if i have to use older version?
Yes, for the more current versions Mozilla discarded all classic plug-in APIs of Firefox.
Either you stay with the last version of Firefox 52 (e.g. Firefox 52 ESR portable to be distressed by update requests as less as possible) or you switch over to Waterfox (https://en.wikipedia.org/wiki/Waterfox)!
Waterfox is a Firefox fork which claims to add all new features and fixes of current Firefox versions in the future. Its sole purpose is to maintain support for legacy extensions.
Even if you have a restriction to use explicitly the original Firefox (and stay up-to-date with), you could give Waterfox a try and simply change its user-agent-string to imitate the original Firefox.