Can I claim My Aunt and Uncle Living with me as dependent care. They lived in my home rent free so I didn't need to pay day care for my 3 year old grandchild.

It depends. 

Your Aunt and Uncle would need to claim the "free rent" as Self-Employment income on their return. 

Additionally, they can not also be your dependents. 

According to the IRS:

"You can count work-related payments you make to relatives who aren't your dependents, even if they live in your home. However, don't count any amounts you pay to:

1. A person for whom you (or your spouse if filing jointly) can claim as a dependent;
2. Your child (including stepchild or foster child) who was under age 19 at the end of the year, even if he or she isn't your dependent;
3. A person who was your spouse any time during the year; or
4. The parent of your qualifying person if your qualifying person is your child and under age 13."