I know the moral side of this is not good, and I agree with everyone's thoughts.
However,
I can tell you for 100% certain that they DO NOT run any check on a persons' drivers license. You are required to present a drivers license to the rental counter and the rental agent must look at it to ensure it's current, looks real, etc...but they don't actually do any kind of driving record check. So if the state she is in doesn't require her to surrender her license (or she ignores the order to do so), then she could easily get a rental car.
If she gets into an accident, she'd certainly get a citation from the police and perhaps her suspension would be made longer. The rental agency could deny liability coverage to her, so it would then fall back to her (or her mothers' if she lives at home) personal insurance carrier to pay the claim. Beyond that, sad to say, not much consequences would come from it. I see people with suspended licenses having accidents more times than I can count.