As you noted, the neoprene straps seem like they might help but they actually tend to exacerbate hair slide. They are great at not pulling hair but they let the strap wander around the head, which makes the neoprene snorkel keepers work well.
And different silicone straps grab hair differently as well.
One thing that often helps is to make sure that any hair is stationary. French Braid or pigtails if possible. Then pull the mask into place from above and don't push it up, because that just tends to make it slide down. Some people who know exactly where a split mask strap will sit, purposely tie the pigtail/braid at that point, and pull the braided hair through the split in the mask. Of course if the braid placement is off, the mask won't fit right, but the strap also will not wander around.
Simple lycra hoods work pretty well too with the standard silicone strap, but they are even more of a nightmare with neoprene mask straps. Getting a one piece rash guard and hood, usually found at spearfishing places makes dealing with the hood easier.
In the end some people just have that shape head that makes the mask end up making ears floppy unless it is under a real neoprene hood. If she is willing to wear an actual neoprene hood, getting a hooded vest does the same sort of thing as the rash guard with a sewn in hood, and does it even better. I love hooded vests. They are useful under thicker wetsuits; they are not so hot they are disabling even in warmer places, and in the warmest places a hooded vest and surf shorts is a nice warm to keep the core warm, and still get a tan on the arms, if that's what she wants.
