That depends on what was causing the cough. If it was just an environmental thing, like dust or whatever, then yes, there's no problem. However, if it was indeed a respiratory disease of some kind that she picked up then she will always be a carrier, even after she has recovered. Your other...
If you can find Tylan 50 the oral dose for a standard size bird is 1/2 cc once a day for 5 to 7 days. Keep her warm and out of the weather and keep a close watch on the rest of your birds. Chickens don't get simple "colds" like people do, they get respiratory diseases. Getting her some...