It's such a large country that it's had to recommend somewhere in particular. Do you know in which city she will be landing in? There is also the question of how much money is she ready to spend on plane tickets alone and what her interests are. I know that there are many Australians that go to Vancouver and Brithish Columbia, Whistler is crowded with them in the winter but I don't know about summer time. The Okanagan Valley is supposed to be nice and so the Rockies in Banff and Jasper, Alberta.
Completely east, Montreal is a very nice city that has a lot to offer and also Quebec City (2 Hrs drive from Montreal) is very interesting since it is one of Canada's first cities where there is a lot of history artifacts.
I'm hope she'll have a great time if weather allows.