- Сказать, сударь, у вас огромная опека! (After all, Sir, you have great guardians!)
I agree with Оля, and I think it's the other way around:

- Сказать, сударь, у вас огромная опека!
=> It should be said, Sir, you have a lot to guard (=care about).

According to Lizie, Molchalin is a guardian/caretaker for all he mentioned, so it's a lot for him to care.