There are so many details that are hard to get from a post. Overall I'd say the most important thing is to find a plan the daughter really wants to commit to because really there is no forcing someone her age to do anything. She has to buy in or it isn't happening. Treating the underlying anxiety and depression is essential.
No idea if this would be a good fit in her situation but an unconventional solution they may not have considered would be to do a version of homeschooling where for the price of Harvard getting her a full time teacher/ educational coordinator person who could help teach her. Some combination of online high school and college might also be considered as well.