I think you should borrow Efrat's cat cam for awhile to determine what is consuming the food.

You know, I often toss out on the back lawn, dry cat food that is given to me by friends (I use only a prescription diet) and it stays there for days. I have seen the following eating it: birds, dogs, cats, chipmunks....and I only assume skunks and raccoons. I am not sure they are all very wild about the flavors of cat food. So I would just leave a wad of dry food out and hey, whatever eats it, eats it. Once Elizabeth comes out of hiding, maybe you will be able to lure her to a better feeding location. I bet she is finding lots of little meals all over the place.....moles, etc. etc. etc.

You might want to leave water out, for sure and maybe some cream, although sometimes it can cause more harm than good. Actually cream is better than skim milk or regular milk.

Have you looked under porches etc? for Mama and kittens?

Keep us posted.