First the landlord will sue her for any damages to the apartment, also for any and all days of lost rent, which will come out of her security, the cost of advertising the apartment.
Remember the landlord is entitiled BY LAW not to lose one days rent on your daughter...and getting someone to rent in the middle of a month is not easy in some paces so who is liable for the rent? Your daughter, thats who.
And then he will get a judgment against her which will show up on her credit report, making it harder for her to get credit or another apartment, and he might be able to attach her paycheck as well...
Not bad.. eh?