I've been following this story since the beginning, it is very sad. Having some experience in search and rescue here's what I think.
She is not a victim of foul play.
She did not drown, the most common cause of death for those not found in 48 hours.
For some reason she left the trail.
It's possible she became injured climbing Lone Mt. Statistically most people who become injured move downhill.
I'd like to know if she had a map. That might influence her direction of travel if she moved off the trail for some reason (maybe for water).
I'd also like to know if authorities have ID those hikers immediately behind her. Who showed up at Spaulding that evening? Did they see anything? Maybe a direction sign on the trail indicating someone left the trail to travel in a certain direction?
What I don't understand, unless she became disoriented, was why she would not just stay on the trail and wait for help if injured. This time of year one would not have to wait long for someone to come by.
I think it's possible she went off the trail for water or a bathroom break and couldn't find the trail again.
Hope and pray for her safe return.