FERPA wins every time in this situation. The locus of control switches to the student, but she doesn't give up her rights: "When a student turns 18 years old, or enters a postsecondary institution at any age, the rights under FERPA transfer from the parents to the student ("eligible student"). The FERPA statute is found at 20 U.S.C. § 1232g and the FERPA regulations are found at 34 CFR Part 99."
We simply have NO legal standing to know anything. (Not that we don't want to know; just that we cannot be informed against the wishes of the student, if 18 or over and against the wishes of the parent, if under 18.)