Agree with Convict, all you need is Prime.
With a consistent and frequent enough water change schedule, you should't need Clarity, as your water should keep itself pretty clean and clear.
Stability is not a bad thing to have on hand, and to use when you add new fish, or medicate your tank, or anything that may cause your tank to have a mini-cycle. Again, the effectiveness of this product can be debatable, but I do have it, and use it as directed when starting a new tank, adding fish, etc, but the need to use it with standard weekly water changes is just a waste of money.
Good luck with your guppies, they are beautiful little fish, but I have never had much luck with them either. I gave up on trying to keep them with my community tank.