When it comes to business (power and money) you will be very surprised who is in your court and who is not. Maybe this friend feels that if she worked for you, it would destroy your friendship. Also, you have the same babysitter etc. All that enmeshment can get pretty tricky.
I am a supervisor of employees....I have found through the years that good work relationships are not built on friendship, but on competency and professionalism. Friendships really can not be brought into most of these relationships because there is authority in being a supervisor. Like it or not that is what being a supervisor is all about. Treating all fair and equitable, not easy to do if it is a friend. JMO
As far as the new job, you really need to find out if the fit is good for you. It really is not about who is coming with you in this job, but what is the best for you and your family. Do they offer different perks? Salary? Does it require you to move? Only you know the answers to those question, never underestimate your gut instinct. What is that voice in your head saying???? Good luck!!!!
Leslie