It's a slippery slope as soon as you start allowing "exceptions" to your rental criteria. What if she was making $150 less than your monthly income requirement? What about $200 less? I wouldn't rent to someone that is short of my monthly income requirement UNLESS there were sufficient compensating factors that would mitigate my risk (ex. co-signer). Ultimately, you still want to be confident that she will be able to pay the rent and the more you allow your requirements to slip, the more likely your tenants will be giving you headaches in the future.
Don’t forget to count any assistance as part of her income.