My first thought was Stroller Strides or Mommies in Motion or any number of programs that do exercise with moms and babies together. She could use that for her group exercise, to meet other moms, and to not have to worry about childcare while getting that part of her exercise in.
And then you could offer to train them at home. You could do both at once, or sometimes if you do a 90 minute session with 30 minutes parent one, 30 minutes together, 30 minutes parent two then you have the opportunity to hone in on each individuals’ needs for a short time and then they get to work out together for a short time. This will work if they have a babysitter or a happy baby. Otherwise, they’re going to need to take turns if baby cries during the 30 minutes when they’re working out as a team.
The thing I stress with new moms is to realize that it’s going to be crazy for a while between being a mom and getting in shape. Also, if she’s nursing, she’s going to have to time when she nurses or pumps so she can work out. I nursed both of my kids until a year, and I had to pump or nurse right before exercise or it was very uncomfortable. If she’s not nursing, that won’t be an issue.