I've been doing body combat for a long time and find it more of a cardio exercise than a muscle toning one, was she doing anything else? I've developed a bit of muscle (not as much as I'd like) but that's mainly from the body pump class I also do. The muscle that I do have doesn't look particularly masculine though.
Personally I don't think a combat class once a week will do her much harm and she could ask one of the gym instructors about specific areas she wants toning so she knows what equipment to use and what to avoid, eg, if she wants her arms toned she wouldn't being doing squats with a bar behind her neck as that would do her legs. It's just about knowing what bits you want to focus on and an instructor could help her with that.