I'm afraid I'm going to take a tough stance here.
These chickens have provided you with eggs for the past 4.5 years and now that they are no longer producing, you want to shirk your responsibility to them and hope to find someone else who will feed and care for them in their old age....since you appear to be against slaughtering them.
I'm also sceptical of people on the internet, especially when they are looking to pass the buck! In my opinion, you owe these hens their retirement or a quick death and maybe they will provide you with one last meal or at least some soup. Palming them off onto someone else is pretty lame... unless of course, you are happy for a struggling family to make a meal from them, but I would want to know that they were killed quickly and humanely.
Probably not what you want to hear, but I feel it had to be said.