It looks to me like she didn't try using words? If this was an 8yo neighbor kid who had shown up to play with your kid, you'd say, "Well, kiddo, I hope you had a nice time, but we're going to have supper now, and we have a full evening planned after that, so we'll have to see you again some other time."

I'm lucky, we have a family story we always reference that is a no-fault no-anger get-out-of-my-house-though-I'm-busy catchphrase. We might say, "Welp, I hate to tell you [catchphrase] but I'm gonna." I think I have been underestimating how useful this is.