@Laura2592 Personally my tendency is to try to explain things to people as long as they aren't being rude or belligerent, but I know a lot of hosts would just ignore it.
So if it were me, I would explain that renting an entire house on Airbnb doesn't mean you can just have as many guests there as you want, up to the maximum, all guests staying must be accounted for on the booking, that many listings have an additional guest fee beyond a base number, as does yours, which is clearly mentioned in your listing information, and it's unfortunate that she seems not to have read the info thoroughly.
You might also mention that had they cleaned up nicely after themselves instead of leaving a big mess, you might have been willing to overlook the unpaid-for guests.