I would suggest doing all of them, just picking one or two may not solve the problem as quickly, or at all;
-Most importantly - make sure their fresh food is in their cage before they wake up. The reason this helps: When a hoarder wakes up, they are already worried about there being enough food for everyone, and he/she is likely a little hungrier from the previous night's guarding the food and not getting enough to eat. If they wake up to no food in the cage, it reinforces their fear and they are automatically put on the offensive for when the food arrives. By having food in their cage before they wake up every night, they begin the calm down realizing that food will always be available, no matter when they are hungry. If you are not able to get their food in their cage before they wake up, be sure to leave fresh water and some kind of pellet food or something for them to munch on until dinner arrives.

-Start giving them extra food - a lot of extra food for a little while. The reason this helps: They learn that there is such an abundance every night and they will never go hungry. (As I said, WE already knew this was true). Once they have settled down and stopped hoarding, you can feed slightly less again. If you have a hoarder, always make sure that there is some food left over.

-Use multiple feeding stations (at different heights if possible) and put each feeding station in a glider kitchen (make sure the entrances are not facing each other). The reason this helps: If there are multiple stations covered by kitchens, hoarder cannot see all of the food dishes or when another glider is visiting them, so they cannot possibly guard them all. Something that helps particularly aggressive hoarders is to set a feeding bowl on top of one or more of the kitchens near the side of the cage, so that the cage mates can come down and swipe a piece of food and run away again before the hoarder realizes they are eating.

-Realize that this problem is not going to resolve itself overnight. The longer the chasing or aggressive behavior has gone on, the longer it will take to for them to settle down. It can take several days to several weeks.

Things you can do to prevent this behavior from reoccurring, once you have it stopped:
-Keep track of appetite levels, if you notice that there is less food left in their bowls for 2 nights in a row, start giving them a little more.
-Continue to put their fresh food in their cage before they wake up, or keep snacking food in their cage at all times, so they have something to munch on until their fresh food can be put in.