Buoyant can mean:
Cheerful, happy, and optimistic
Able to float (in a different context)
In the sentence, "buoyant steps" suggests light, lively, cheerful steps, indicating that the person is in a happy mood.
Option Analysis:
A. muffled ❌ = quiet or indistinct
B. cheerful ✅ = happy and lively
C. noisy ❌ = making a lot of sound
D. unhappy ❌ = sad (opposite of buoyant)