A U visa is for persons who have been victims of crimes and are assisting law enforcement or in the prosecution of the perpetrator. She probably will not quaily because I assume the case has been disposed of. She may have other means of adjusting through one of her family members. I suggest she consult with an experienced immigration attorney to determine whether she has any alternatives.
Attorney Mulder appears to be correct.
Meet face-to-face with an attorney to double-check ... bring the denial letter with you.
FORMER IMMIGRATION LAW PROFESSOR -- LEGAL DISCLAIMER: This answer is offered for informational purposes only. It does not constitute an attorney-client relationship.