What are the legal rights of a biological parent regarding a child that has been adopted?

We live in California. My younger sister just turned 17 on the 13th. Her and her mother (my step-mother) got into a huge argument and my younger sister has decided to have her biological father pick her up, so she can spend the night at his house. She insists that because she has told them where she is going and she is 17, that she has the right to go to his house with or without the permission of her parents. The bio-dad claims he has a right to pick her up, in this situation, with or without the permission of her adoptive parents. Our dad has called the sheriff and is having her listed as a runaway… He is also talking to the sheriff about charging the bio-dad with kidnapping. Also, since my younger sister told them she was going with bio-dad for the night, our dad has been talking shit about bio-dad, her boyfriend, and her.

I have a few questions.

As a seventeen year old, in California, DOES my younger sister have the right to determine where she is going without parental consent?

Does bio-dad have a right to remove her from her adoptive parents’ home without their consent?

Assuming the answers to the above are no, what sort of legal action should bio-dad and little sister expect to be taken against them?

Would you agree with me that the adults in this situation are all behaving poorly?