If the pups were close to being weaned, they are probably fine. The other adult coyote should still be feeding them. But the adult won't be at the den site very much. So the neighbors wouldn't probably see it.
The worst thing the neighbors can do is to feed the pups pet food or scraps. A coyote that does not have a healthy fear of humans is a coyote that will likely cause problems down the road. I know the neighbors are trying to help, but feeding the pups isn't the way to do it.
I'd suggest calling Flint Creek Wildlife Rehabilitation (847) 842-8000 to see if they have someone close enough to go take a look and access the situation. You don't want to take the pups if the other parent is still around caring for them.
Let me know how things turn out.