Can you breakyour lease if you are not safe in your apartment?

As a general rule, safety concerns are not a reason for violating a lease.  So she may not be able to break the lease without penalty. However, there is something called the "implied warranty of habitability," which means that premises must be safely inhabitable; there is another called the "covenant of quiet enjoyment," which means a tenant must be able to make use of their premises with without undue disturbance. Either one could potentially (not automatically) be used as the basis for an early lease termination regarding safety related issues, as long as the landlord is responsible and has control.  Therefore if the landlord is not taking the most basic security precautions, such as by having locks on exterior doors, providing light in common spaces, or (as in your daughter's case) not providing a screen door, she may have a validreason for breaking her lease.  On the other hand, if it's simply that it's a bad neighborhood, that is not the landlord's responsibility unless that is the criminals are other tenants or if the landlord completely misrepresented the neighborhood to her and she had no opportunity to investigate the neighborhood before moving in (so she totally relied on what the landlord said).

Even if she can't terminate her lease, she still may not be liable for all of the remaining lease payments.  Landlords do have a duty to "mitigate" damages"; that is to minimize their damages by re-letting the premises.  This means that if she breaks the lease, her landlord has to advertise the place to try to find a new tenant, and once they do, they have to let her out of the remainder of the lease term.  However, that will still almost certainly result in her having to pay for at least a few months more but it is a better alternative than paying for the remaining 12 months.

At this point she should speak to a tenant's rights organization or an attorney that specializes in landlord-tenant law.