Am I eligible for any dependent or education credits or deductions?

Hi there! I am actually asking this question for my mom, who is single and files as head of household. Our household includes myself, my mom, and my brother. I am 24 years old and a full-time, second year graduate student. My brother is 26 years old and a full-time, first year undergraduate student. I am fairly certain my mom can claim both my brother and I as dependents (via "qualifying relatives"), as we live with her full-time, she provides more than half our support, and neither my brother nor I made more than $4,050 in 2016.

My question, however, is whether my mom can claim any type of dependent or education credits or deductions when she files her return. She claimed the American Opportunity Credit for all four years of my undergraduate career, so I know that is no longer an option, however, I am wondering if she can still claim it for my brother, given his age, but considering this is his first year in college?

My other question, and truly this is really where we are most concerned, is if there are any credits or deductions my mom can claim that are refundable? For example, I know the Lifetime Learning Credit can be claimed for me still, however, it is not refundable, so not all that helpful for our situation!

I sincerely appreciate any answers--and thank you for reading such a long post!