Words fail me! I can not imagine how you must feel or what would drive a mother to take her children to that awful place.
As you said Cape Town has some true beauties and SA itself is one of the most gorgeous countries I've visited. But the horror and atrocities that I witnessed there still stay with me now (10-12 years later).
I would do anything in my power to stop my children ever having to experience the way life is to the uneducated people of SA.
All we can hope is that your daughter, who previously had no responsibilities in SA and as you said will only remember the nice things, soon see's the hideousness that exist in what you rightly call "hell".
I have everything crossed for you that she returns here safe and sound with your grandchildren very very soon.
As an adult (all be it a young adventurous one) is she now aware of the real dangers that she will be facing there? You said you sheltered her from a lot of the bad things when you lived there, but does she know now what it is like.
I hope this doesn't leave to many scares in your mother / daughter relationship.