Is my family trying to help or make her look bad?

Sure, your mom and sister are trying to help. Maybe your girlfriend just feels bad whenever your mom and/or your sister does something nice. They are just trying to warm up to her, but she's giving them the cold shoulder. Talk to both of them, tell your mom and sister that she likes to be independent, meanwhile also tell your girlfriend that she needs to respect your family. If you don't solve this problem quickly, it could end in a breakup or a big feud between your girlfriend and your family. You don't want this.