It sounds more like termites than ants. Termites will dig thru concrete to get to wood. I know that from first had experience.
I'd suggest calling in a professional exterminator. There are times when it really is needed.

They definitely aren't termites. They're just tiny ants that like catfood. lol!

Have you tried Antbloch?

You can get it at HD or Lowes. I used it every year, sometimes a couple times a season.

Sprinkle it around the foundation of the house and in a few days they will all be gone.

Check with your county ag extension service. There are enough species of ants doing different things that you need some local advice.

Here is a link that might be useful: NY extension

My all purpose fix is borax mixed with sugar and flour....but it they are eating cat food....mix borax with some cat food...BUT...MAKE SURE to keep that away from the cats. Borax is not as toxic as other ant poisons but it's sure not good for kitties.
Actually they are grease eating ants.....tiny teeny red ants?
The old trick of borax and peanut butter or bacon grease may work better. Boron is toxic to ants, they take the yummy stuff you mix back to the nest to feed the queen and the babes and it wipes them out.....theoretically!
Linda C

Since your friend really doesn't know what they are dealing with, calling an exterminator seems the smartest thing to do.

We recently had an ant situation starting, also going after our cats food. Very small ants, almost couldn't see them. One treatment from the exterminator and they have disappeared from the house at least, although I still see them around the back steps (they were coming in through our patio door). If I remember correctly, they will be back for another go-round at some point.

I'd rather spend a bit of money to make sure they are completely eradicated safely. They worked from outside the home, not inside where the cats bowl is, and where obviously the nest of the ants are.

Thank you all for the replies!

He found a liquid borax ant killer (it was the next least-toxic option to try), baited some catfood with it, and it seems to have done its job! yeah! He just wanted the safest thing to use around the cats.

I'll try to remember that PB or bacon grease trick, and Antbloch for future reference. I never thought to check with the county ag dept -- they're a great source of info!

Thanks everyone!