Deb, you've already got some great advice on here.
To add my perspective - we go to a playgroup each week and have been meeting since our kids were about 3 months (one of those council mothers groups). It has shown me how very, very different children can be! We've got a couple of kids who talk as though they are 4-5 years old already, and some who have limited speech (like my DD). Kids are all so different in their development.
Your friend just doesn't have enough to keep her occupied by the sounds of things.