They just need some good quality 2nd cut grass mix hay, possibly with some alfalfa mixed in it given to them free-choice(all the time), fed off the ground.
When they are around 30 days from their due date start giving them some Goat feed, I prefer pelleted. start with 1/4 lb and after 4 or 5 days go up to 1/2lb and after 2 weeks or so go up to 1lb, feed one time a day.
Also, 30 Days before kidding you can give them a CD&T vaccination( from any feed or farm store), this is 2 cc given sub-Q. If they have never had a vaccination they would need a booster 3 to 4 weeks later.
I would also recommend giving them a Bo-Se shot, this can be purchased from your vet. It is given at the rate of 1cc per 40lbs, Many people give this 30 days before kidding, but can be given anytime. This will help you have much stronger kids. And helps prevent White Muscle Disease.
If you don't know anything about shots, you may wish to call a vet and have him come out and give the shots and teach you what to do. Or find a local farmer to help.