Anybody got a recipe for a beef stew got to feed 100 homeless

Once upon a chef has THE most excellent recipe for beef with carrots. It's the only one I use.

If you search online, you'll find many recipes for cooking for a crowd or cooking for 50. Use one of the beef recipes.
For economy, you can reduce meat to about 2-3 oz (weight after trimming) per person and fill out the stew with a combination of root, green and red/orange vegetables.