Some will molt and begin laying again, but many will just waste away. When harvesting the giblets, remove the ovaries and egg-making plumbing, which always includes an assortment of developing egg yolks in various sizes. They're as edible as the cleaned gizzard, heart or liver. The only way to tenderize an old hen is to simmer it for hours in a stew. Even then, the white meat will be dry and ropy.
Dark meat can be strong-tasting and tough.
Concentrate on making a rich, flavorful gravy and a lot of fat dumplings to go with the often-disappointing meat. A good flavor-enhancer is to add to the cooking water a chunk of the internal, hard fat removed from younger birds slaughtered earlier and frozen. Perhaps the best use for old hens is to cook, bone and dice or grind the meat for use in breaded croquettes or patties, cooled in jelled cooking juices for lunch meat, or spiced in hen sausage. The skin and bones of an old hen lack much flavor when stewed, so you can save time and avoid gutting and plucking by skinning and fleshing the least plump birds. Using stout shears that will cut through feathers, cut skin around neck and down the breast.