Good job calling the Humane Society. That is a hard thing to do (I did it once). They often say they can't help and then see what they can do.

I wonder WHY she has cats, if she doesn't care about them. I'd say try to find another home for them and then make them go POOF, except she would just get more. So that doesn't solve the problem long term, just for these 2 kitties.

Let's see what others offer for ideas.