If she cannot answer “Yes” to any of the dependency questions:

were you born before January 1, 1984

are you a graduate or professional student

do you have children you support

do you have legal dependents

are you an orphan or ward of the court

are you active duty in the U.S. Armed Forces

are you a veteran of the U.S. Armed Forces

then she is considered a Dependent student and needs your information to help complete her FAFSA. Once the FAFSA is completed, it will generate and EFC (Expected Family Contribution) that schools use to determine what type of/how much aid a student is eligible for.

If you have further concerns regarding why your ssn is needed you should talk to a financial aid officer at her school for more information/guidance. Good luck!