There are so many directions she could go with crafts. Your friend may look into whether there is a theme of the month or use something like the seasons as a guide. Another idea would be to do something related to the various activities such as sewing, growing veggies, farm animals, etc. See what the kids are eligible to enter into the fair and look up an appropriate craft. Have the kids make things for their groups fair exhibit.

For spring:
Grow herbs in a tin can. (This idea could be simplified.) http://crafts.kaboose.com/earth-tin-can-herb-pots.html

This site has some simple ideas. http://www.create-kids-crafts.com/bird_crafts_for_kids.html The kids have opportunities to raise chickens so the baby chick craft might be great for the younger kids.

If your friend has a portable microwave or a toaster oven, basic cooking can be done.

She may also want to get on the official 4-H web site to see what others are doing.

Here is a link that might be useful: 4H website