Parents/family who try to influence university decisions like this annoy me. Apply to where you want. Emma is a lovely college. But I'm also sure you'd be happy enough whichever college you were at.
The whole application statistics thing is just silly, in my opinion. If you're supposed to get in, you'll get in. That's my opinion. I know some people will disagree with it. If you want to actually look at the stats though....in 2011, 27.5% of Natsci application to Emma got into the University (note not necessarily the college). For Downing it was 28.2%. Caius was 33.3%. Fitz made 28 offers, but 11 of those were from the pool (for example to the people who applied to Emma!). The overall success rate if you applied to Fitz for getting into the Uni was 22.9%. For Robinson it's 21.9%.
But don't think the trend necessarily falls in the other direction. Pembroke had a 20.3% success rate.
I'm not good at maths so correct me if I've interpreted the stats wrong. Also I am not saying that Fitz and Robinson aren't good college - in fact for my subject they have some of the best fellows in the university - but I'm just trying to give a cross-section/idea. I hope this helps - apply to the college you want to be your college!