There are any number of special things she can bring back from Greece, but beer isn't one of them. Metaxa, Ouzo, wine (google Vinsanto), oil are all better options.
As mentioned, there is Mythos and a couple of other brands, they are all Heineken clones more or less. You aren't missing much.
I wouldn't expect much from the Hillas craft beer, frankly its probably not worth the effort to track down, considering they would have to import pretty much all of the ingredients and they are a long ways from where that stuff it typically grown.