Resignation without offer letter with a bond

Hi, 

My wife is suffering from health issues so she is unable to continue in her current job. But she has signed a Letter of Intent having a bond of 1 year (not on stamp papers). She was told she will get an offer letter on her joining date but she has not received it even after working for 2 weeks. Now she doesn't wants to continue the job. Does this imply that she has to pay the bond amount?