What can I do about our rude neighbor?

She and my mom have been best friends since I was born but she just seems snooty to me and I don't like her. She shows up at our house every day, sometimes more than once, completely uninvited. Today she just walked right in and didn't even knock and no one was at the door. She just shows up at our house and my mom gives her like half our food which is really annoying. And I'm not really bothered by any of that, but she stays for HOURS. We don't even invite her and she will come to our house on holidays where we are supposed to be spending time together and anytime she wants without even asking if it is okay with us. I told my mom I was bothered by it and she said that it wasn't rude to her and they are best friends, but I really think it is inconsiderate and she is taking advantage of our family. I want her to quit coming over all the time and I don't know what to do! Help!!!