If she has personally signed a lease, she is obliged to pay the landlord the rent for the next 10 years.
She will be able to sub-let it with the landlord's consent. However, she still remains liable for the rent which she must pay to the landlord. if she can let it for more than she is paying, she keeps the difference. If there is a shortfall, she has to make it up.
She can enter into discussions with the landlord. He may agree to accept, say one year's rent, if she hands back the keys now. Of course, he could refuse and insist that she sticks to her lease.
This obviously assumes it's a standard lease with no break clause or provision for early termination. So first, of all read the lease. If you don't understand it, ask the solicitor who advised her on entering the lease in the first place, if she used a solicitor.