You can't help people who don't want help.
Your father starting his own emergency fund is a brilliant idea - make sure she doesn't know about it / can't get access to it.
If he's going to start shutting down the credit cards I'd recommend doing them one at a time, and making up some reasonable sounding excuse for it in case she questions it. (Not as easy now with the new laws, but I'm sure there's something she'd believe).
Nobody can force her to do what you believe to be the right thing for her, though, and trying to force her into it will only cause resentment. You can't control her, only your reactions and interactions to/with her.
He needs to take steps he feels comfortable making to minimize the impact to himself, like the emergency fund, etc, but again - he can't control her actions, he can't "fix" her problem for her. She has to want to get better on her own, and trying to force her to get to that point will only make matters more difficult.