The spot where her body was recovered was not directly below the summit cliffs, but south of that. You would have to purposely leave the trail to end up where she did. The spot is closest to the new Heartbreak Hill Trail. It is very steep where it departs from the PCT, gaining about 1,800 vertical feet in less than a mile. Based on the effort it would take, she was definitely on her own two feet up there. But again, most "slips" on the trail would have you rolling through the forest on the south and west, not over the edge. Even where the trail approaches the edge, there is often a "lip" to it.

There was sufficient time for a strong hiker to make the summit before dark, but it absolutely would be dark on her descent. Other than the last 400 - 500 vertical feet, the trail is good enough to navigate safely by headlamp. Avid hikers generally have those in their backbacks just in case.