it is somewhat of a tough call and here is my 2 cents...kids get bored with things really fast and mom better be prepared to be mother duck as I am afraid they will end up being hers alone to tend to...ducks surely are not toys...mom needs to educate herself so she can educate the kids and supervise them with any and all pets...
I still have nightmares about the post Easter chicks, ducklings, goslings and rabbits my father would bring home from his city routes about two weeks after Easter...a lot of them were injured by kids tossing them around and mis handling them...many were starved because people did not know how to feed them properly...a lot of them were dirty...I guess people did not realize that the little fuzzy things would eat and poop a lot...
With that past experience, I would really have to have a brain fart to let kids have the ducklings...I would, if I let them, hand them a "how to" flyer on care and feeding and make contract to take them back if the people got overwhelmed...
just some thoughts...