My 2 year old treats her grandmother kind of mean. What can I do?

She seems fine with everyone else but is kind of mean to my mom, (her grandmother). My mom is very good to her, but for some reason she isn't as friendly to her as say, my sister. My mom can't help but get a bit upset when her only granddaughter does not respond kindly. I'm actually starting to get stressed out about bringing her to my mothers because I feel the repercussions of my daughters actions. I know she's only 2 and doesn't mean to be hurtful, but as I learned first hand, it does hurt your feelings. Any suggestions would be great.