For those following, my hen has made a full recovery. Last night I fished her eye out but she still wouldn't open it. Then this morning she had it open half way and was eating well, walking around normally but occasionally scratching near that eye. I suspect that is where she was stung. I put her with the flock and checked on her frequently. By night fall her eye is all the way open and she has been up on the roost. Yippee! So, I'm not really sure why the Benadryl worked for those asking but I'm almost positive she would have died without something. Her breathing was so shallow, etc. With as many bark scorpions as we have here I will be sure to keep Benadryl on hand for any future stings.
Thank you for all your help!
After flushing her eye with saline solution, apply terramycin eye ointment for a few days. You can use neosporin ointment if the terramycin isnt available.