Leave food out, maybe make up a warm place for her if you feel she has no place else to go. A cardboard box with old towels or blankets is better than nothing to her. If you can ger to the market, cat food would be best for her health, but in the meantime, anything - dog food, leftover chicken, etc works to fill her tummy. Put out fdresh water too. People often forget they need a clean drinking supply.