For openers, you can say "I head about the accident...are you okay?". She'll either want to talk about it or not.
One of my son's classmates killed someone at 17. It was first degree murder. Long story.
His mother had begged a judge (prior to this) to put him in residential treatment, but instead they put him in a program where they find an apartment for teens and offer minimal supervison. Go figure.
To cut to the chase, I encountered his mom shortly thereafter and what does one say? I just said "How have you been?" After that, she just started talking about how awful she felt about it.