My best friend's mom hates me?!?

It all started a long time ago on my best friend's birthday party. We were having a sleep over so I brought a bag of all my things and just threw it on their sofa. So that night, I left my bag wide open so I could always just reach in to get my toothbrush and pj's and my best friend had a birthday card of money and just threw it on the same sofa I had my bag on. Then the next day, her money was gone and it ended up in my bag! So now her mom thinks I fully intended to steal it when it was just an accident. Her mom told a bunch of parents about this and always talks behind my back when her mom doesn't like people who back talk in the first place. Every time something that belongs to her mom goes missing, she says "Oh did she take it? Was she here today?" when I haven't been to her house or seen her in months! My best friend even told me on the phone that her mom's wallet went missing in their house and that her mom wanted to see a psychic to see if I did take it. But just this weekend, I finally had a chance to see my best friend. She asked a week ahead of time if I could sleep over again and her mom would always make up excuses to say no but her dad decided I could sleep over. I was so excited to see her again and last minute, (it was seriously last minute, like I was already in the bus going there) she calls me on my cell phone and says "My mom said that you can't come over anymore, she said if you come over that my parents are going to start fighting." I was shocked! Like what does having me coming over have to do with anything?! Her little brother can ask whatever and whenever to have a friend come over. So what can I do to make her trust me again? I have apologized a lot and I'm always nice to her. I honestly don't care what her mom thinks of me but now it's interfering with our friendship.