Can my Mom still claim me? I am 18, I live at home, pay no rent, my Mom pays all my healthcare needs, buys my clothes, etc. I made 8,500 last year and filed single.

Yes, she actually can still claim you. If you are under 19, live at home, and she provides over 50% of your support, then she can claim you. 

However, if you have already filed as single and not a dependent for 2018, then she cannot claim you without you amending your return.