Is it possible to complete Heartache by the number AND kill the Crimson Caravan lady + The Van Graafs without losing NCR rep?

I really don't see why you lose NCR rep for killing the Crimson caravan lady as she is evil..

Thanks

Yes. You don't need to kill them. You can actually GAIN NCR rep if you do the diplomatic solution of finding evidence against their illegal activities. But I do believe you need to pass a speech check with Cass before you get the optional quest legs to do that. Though, I suppose if you know where to get the evidence, you don't NEED the quest legs.