Broke lease terms on day 1

[Marcin Nurek]

Back in June I have received a security deposit and in July first month payment for a lease starting on August 1 move in date. On August 1 I was informed by the tenant she is breaking the lease due to some family issues and will not be moving in. First she acknowledged loosing security deposit and first month rent, but now she is asking for some refund.  What would you do, keep it all or refund half? If I refund, I will be at loss. The place is vacant now and my next tenant will move in on September 1.