Yes, you may still get Food Stamps/SNAP benefits. You will need to report any new household members right away to your worker/the food stamp office. It's always best to do that in writing. Ideally, you should bring in a letter to the office and get a date stamped copy for your own records, to prove that you reported her moving in. You will also have to report whether she is buying and preparing food with you, as well as her income and resources. Whether you will continue to qualify, or if your benefits will increase or decrease will depend on those factors (if she is sharing food, if she has any income/assets). Remember to appeal any notices about your Food Stamps that you don't agree with.
This "answer" does not constitute legal advice and does not establish an attorney-client relationship. It is meant for general information purposes only.