You can give them to people who want them, can take care of them, and benefit from their eggs. Win-win for everyone. If you don't feel like taking care of them; that is nothing to be ashamed about or your fault! Animals need time and money, and a lot of times you just don't have that time or money. I would like a big pig, but I don't have the time, money, and live in a city centre and my neighbours wouldn't like the smell.. I would like a zoo if I could! But I can't. Not because I can't give the love, but don't have the time, money and room.
Ducks can reach an age of 15 years! I would look for a better home, and tell your friend that you really liked the gesture, loved the ducks, but unfortunately didn't have the time to give them them proper attention they need with your study activities.