An Ant? Well they're pretty small creatures, so not easy to find, make sure you're webcam isn't blurry and try again!
But Serously, I don't know. I can run MV just fine, and have never heard of "Ant"
It seems as if something important named "Ant" is needed to run your thingy. And Ant is installed but the file build.xml is missing from Ant. Go to where Ant is found, (dunno what Ant is) and see if you can find a moved copy of build.xml nearby, if not you need to re-download whatever Ant is. It also seems something in your JS folder of your project uses whatever Ant is, and cannot find it whenever what is using Ant is run, which if it's a script, will run straight away, pretty much.
Are you sure it's not since build.xml needs to be on the device on which you play the game that uses the script with Ant being used?