I'm joking around with my mother but our maid got offended
Why did your maid get offended? Is it because you were joking with your mother in front of her? Was that wrong in some way?
I don't think it was wrong, but she's just too naive
Senses of humor varies among people and what one person considers acceptable may be considered offensive by another. If a joke that you made offended someone else, you should acknowledge that their response is just as valid as your own opinion and you should apologize for the offense you caused.
But my mother yelled at her for being offended. I'm like omg, why would you yell at the maid for that?
Well, try to think about who is around you before you do anymore jokes. This makes sure no one is offended therefore no ne gets yelled at either. If someone is offended though they should be consoled and not yelled at.