What these two "women" (and I use the term loosely) did is unconscionable. But what you are recommending is punishing the child for the sins of the parent. These kids had no say in how they were born or conceived. It's not their fault that they are deaf. To deny them any services that other similar children would get only because they had "normal" parents is just plain wrong and misses the point.
A better response would be to have Child Protective Services come in and rule the mothers unfit and take the children away. Any legal action that can be taken against the mothers should be taken. But I doubt there's anything on the books to cover something like this.
I agree with you, these sick people must foot the bill for every expense associated with their diseased handiwork.
But I would go further, this should be treated as an act of violence identical to plunging an ice pick into a baby's ear to achieve the same result.
What's the difference?
Child abuse is child abuse by whatever means, this is actionable and a message must be sent that designing children to produce handicaps will not be tolerated by society.
That's what the law is for IMHO.