She said earlier in the coffeehouse that she dropped off Emma at her moms so she could go and get things arranged in Paris, and her mom was flying out with her over the weekend...
Someone says poor mom, being on a plane for 8 hours with a baby... and Rachel says not poor mom, poor Emma to listen to mom talk about Atkins for 8 hours... (I think it was Atkins that she said, not positive).
All the events happened in one day, so it would make sense that they didn't stop to get Emma at her moms house out of the city before meeting up with everyone.