I'm not quite sure what to do - family situation

Joelle
I've never written a personal story like this in here, but I'm honestly at a loss and have no idea what to do. 
I just found out that my half sister, who is only 16 years old, was kicked out of her house. Our dad is a deadbeat, but thankfully I had an amazing mother who gave me the world. Her mother, on the other hand...well she just kicked out her 16 year old daughter for no reason that "she just doesn't want her there anymore."
I am so furious and scared right now. Apparently my sister is staying with a friend, but that's just unacceptable in my mind. She's such a bright kid, and has SO much potential. 
My husband and I live about 2 hours away from the rest our family, or else she would be moving in with us in a heartbeat, at least until we figured out what we were going to do in the long run. 
My family (my mother's family) isn't well off by any means, but we were stable. I don't doubt that my mother would take her in, but that's not fair to her and my stepdad. My dad's family is...erratic, and while I love them all to death, they aren't the type of people to take in my sister and provide her a stable home. She can move in with my grandparents (they almost always have at least one of their grandchildren living with them), but my dad lives there - and my sister doesn't have a good relationship with him at all (just like myself). Her mother doesn't have any family. 
I can't help but feel like it's my responsibility to figure out what to do. I'm 29 and my husband is a doctor - we have a nice home and we can provide the stability she needs. But again, we live two hours away...and I'm 31 weeks pregnant. I want to do whatever I can, I just feel so helpless. 
I just needed to get it off my chest and see if any of you have a similar experience or words of encouragement? I would really appreciate it.