grepping /Library and "Too many levels of symbolic links"
The Mono.framework neither belongs to Apple nor is it installed as a part of Xcode. I've cross-checked that with a VM (10.8.5/Xcode 5.1.1) 

Checking your profile i'd suspect it was installed with Xamarin (or another cross-platform dev environment).

IMHO your Mono installation is hosed/got corrupted. A proper install looks like this (/Library/Frameworks):



Your path to Mono looks like this: /Library//Frameworks/Mono.framework/... (Please notice the double slash in the path).

So check your disk with Disk Utility first, then delete Mono.framework and the superior no name folder (or whatever it is), download the latest Mono.framework installer and reinstall Mono.