How do I handle toddler tantrums?

I have been babysitting a good friends 2 year old daughter for about 3 months now, and she’s usually pretty calm, but she throws several tantrums every night I have her. Her tantrums last anywhere between 5–20 minutes, and she fights sleep at night so she gets even more grumpy because she is tired. I cut way back on her sugar so she wouldn’t be so wound up but nothing changed. I try to feed her healthy food as well. Also, she doesn’t really talk yet. She can say “ball” and “hi,” but I think that is mainly because no one has the time to MAKE her talk. She’s really quite strange. She doesn’t seem to have much of an attention span at all. When I try to pacify her during a fit, she doesn’t appear to notice anything I’m doing. When I try to get her attention, I literally have to clap my hands and call her name over and over again. She’s had her hearing checked, and you can tell she isn’t hearing impaired because she’ll hear a necklace hit the ground and go bonkers for it. (She loves necklaces!) So I guess…I don’t know haha! I have an autistic nephew and a deaf nephew, and I babysit them both…but none were this…difficult to pacify. She just doesn’t seem to notice anything. What can I do?

**Also, her mom tells me the little girl loves it at my house, and she seems generally happy. When she gets here, she comes in smiling, and she’ll hug me and go straight to my room and crash on my bed. I don’t mistreat her or anything like that but I honestly don’t know how to handle her.