Here is the description of guardianship for FAFSA: Federal Student Aid. It’s important to note that colleges routinely require documentation. My suggestion is to contact the college financial aid office & explain the situation. Ask to speak with someone who reviews guardianship claims on FAFSA.
It will either be that parent information is required, in which case it sounds like the EFC would be low, or the student will be independent due to guardianship. In this case, any student income and/or savings is assessed at a relatively high rate, so if the student does work and/or have significant savings, the EFC might be a bit higher than expected. The guardians will not have to provide information on FAFSA, in any case. It’s possible at Profile schools or some private schools that have their own form in addition to FAFSA that guardian information could possibly be requested. This is dependent on the individual school policy.