Extreme pressure wheel bearing grease. Not to much that it gets on the brake shoes. Disassemble and clean everything real good first. If you remove the axles, only remov one of the bearing cone nuts. Keep one in place so the axle is centered when you put it back together. You do not have to remove the bearing cups in the hub, just use a clean rag to get as much of the old grease out as possible.
Put a coating of the wheel bearing grease about an 1/8 of an inch thick in the cup. Drop the round bearings back in and press them into the grease, one at a time, that will hold them in place. Put a little grease on the bearing surface of the cone nuts when putting the axle bacl together so they are not riding on bear metal when you tighten everything up. They should have no play and turn free with minimum drag. After everything is set right wipe off the excess grease that comes out of the cone nuts.