Getting back after 3+ years?

How hard would it be to find a job after being gone for 3-4 years due to raising young children? A hospital job, that is, on a med/surg or any other floor.
Taking a nursing refresher class would definitely show employers you are doing everything you can to get back in the game. Interviews today focus on customer service, interpersonal (professional) relationships, conflict resolution and such. Of course, I don't know your local market. The more prior experience you have the better. You won't lose anything by applying, good luck.

Hard. The hiring market is very different now than it was 4 years ago. Network if you can.

Well start applying and see where it takes you. It won't be easy, but you never know until you try.