It had to be Danny who followed Helen, because he is team leader, and 'hero' of the show, so he has to be the one to defeat the 'bad guy', no matter that it would make more emotional sense for someone like Connor to be the one who confronted Helen. Unfortunately, that's just the way tv shows are sometimes, especially shows like Primeval.

Plus, once Connor was injured, Abby woud never have left him behind.