@Aluaa,
First of all, what country are you in? I would assume this is the US... but I am not sure. Tthe US culture is the only one I can definitively answer for.
I am not sure what you are afraid of. You friend needs a best friend right now. For you to meet with her, to listen to her, or even to help her contact her boyfriend is not illegal and there is nothing that her crazy parents can do to you. I don't think you are putting yourself in any real risk. You have to be careful that you aren't going to make things worse for her... if there are drugs, or something going on other than just strict parents, then you wouldn't want to support her. But, there is no harm in listening to what she has to say... and she needs a friend no matter what is going on.
I would certainly meet with my friend in this situation, and I would listen to what she has to say. And, unless there was something illegal or dangerous... I would probably help her contact her boyfriend or to get what she needs.
If the parents are being abusive, there are things that a 16 year old can do. You might consider having her talk to a school counselor or finding some adult you can trust who will help her with her parents. In most places in the US there are family services agencies that will do the right thing.