Helping a friend . She is a college student. Her parents are not claiming her for 2020. She lives at home, doesnt pay rent. Is she eligible for either AOTC or LLC?

We cannot answer that.  We cannot see any information.    We do not know if she worked, how many times--if any-- the AOC has been used for her.....etc. etc.  And that she is not being claimed does not mean she cannot be claimed.   The rule is if she CAN be claimed she is supposed to say on her own return that she can be claimed as a dependent.

https://ttlc.intuit.com/questions/3262983-who-is-eligible-to-take-the-american-opportunity-tax-credit

https://ttlc.intuit.com/questions/1901526-what-s-the-income-limit-for-the-american-opportunity-and-lifetime-learning-credits

https://ttlc.intuit.com/community/credits-and-deductions/help/what-expenses-qualify-for-the-lifetime-learning-credit/00/26844

https://ttlc.intuit.com/questions/3262984-who-is-eligible-for-the-lifetime-learning-credit

https://ttlc.intuit.com/questions/3383321-why-didn-t-i-get-a-credit-or-deduction-for-education-expenses

https://ttlc.intuit.com/community/dependents/help/when-do-i-have-to-answer-yes-to-being-claimed-as-a-dependent/00/1994319

Q. Is she eligible for either AOTC or LLC?

A. Simple answer: No.  If she can be claimed as a dependent, whether she actually is or not, she is not eligible for a tuition credit*.

Furthermore, there's a new urban myth among college students that says they can get a $1000 from the government just for filing a tax form. For most of them, they simply aren't eligible. A full time unmarried student, under age 24, even if you don't qualify as a dependent, is only eligible for the refundable portion of the American Opportunity Credit (AOTC) if he supports himself by working. You cannot be supporting yourself on parental support, 529 plans or student loans & grants. You usually must have actually paid tuition, not had it paid by scholarships & grants.  It is usually best if the parent claims that credit. 

*If the student actually has a tax liability, there is a provision to allow him to claim a non-refundable tuition credit. But then the parent must forgo claiming the student as a dependent, and the $500 other dependent credit.  The student must still indicate that he can be claimed as a dependent, on his return.