Okay, setting aside the atrocious grammar... she seems to be making an argument from evolution here. It's biologists who claim that life may be unlikely, but it only has to happen once... and given the size of the universe, even a really, really low probability would be enough. The universe, is after all a really, really big place. (Dare I remind, however, of the comment I made on yesterday's post that god is a one-off event, not a repeated phenomenon. In looking at the whole universe, there are many occasions for life to get started... giving us an expectation value larger than one, but since god either is or isn't (supposedly), the expectation of a single improbably event is still very, very, very low.)
But theists don't think life is improbable. Most believers claim that life, and our kind in particular, is essentially necessary because their god created us. So how is life improbable according to that worldview?
There is also a gross misperception in what this claim seems to suggest about her definition of atheism. To be an atheist, one doesn't have to believe that a god is impossible, only highly improbable, and actually, even just more improbable than not will do. To get to impossible, it depends very much on the way one defines god. God becomes impossible when his believers define him in grossly, and blatantly contradictory ways. Those gods are impossible, but the more vaguely one defines god, the more likely an atheist is to simply say that it's improbable, not impossible.
Of course, maybe this is too complicated for your theist to understand? Maybe just point out that allowing that something could exist, doesn't mean it does exist... Russell's teapot, anyone?
I think someone needs to send this theist a dictionary and explain to her what a proof is... Maybe I'll look it up for her tomorrow. :)