500 calorie diet is the worst idea ever. What is she going to do when she goes back to eating normally? I'll tell you what, she is going to rebound and end up fatter. Happens with every crash diet out there and it will also happen if you make her do some of the other extreme diets recommended here as the one of pure protein.
Also, she weighs 67 kg at 1.65m...that seems to be a healthy weight imo, why do you want her to lose more?
dj is correct, go by the mirror, if she wants to tighten up a bit or lose some extra fat. Training will be very important, I think dj's advice of the metabolic type workouts is great...much better than the bbing type of split you're making her do.
Most importantly, don't make her crash diet, that will mess up her metabolism and will make her regain everything once the diet is over. Because let's face it, is it an eating pattern you can sustain forever? of course not. A calorie deficit of maybe 500 (you will need to figure out her maintenance levels accurately) would be enough...and as pointed out here, make sure she isn't eating more than what she tells you.