It is possible to make Server respond with irrelevant data if it is scanned with Nmap? If yes, are there any examples of such SW?
Snort can do what you’re asking. It can detect various types of network scanning behavior, and apply rules to respond with whatever kind of packets or data you configure. Plus, one snort appliance in your network can protect all the systems in its scope, not just one server at a time.
It isn’t exactly what you asked, in that it’s not a modification to a web server, but that shouldn’t matter if it does what you need.