Muzan was preparing to cut through the Hashira and remaining Slayers until his tendrils were cleanly cut off.

Muzan: “What the..!?” *Muzan says as his eyes and sense of smell searches for the cause of it.

Gyomei, Sanemi, Obanai, Giyu, Inosuke & Kanao: They are all awestruck and confused at the sudden save. Zenitsu & Mitsuri: “W-what just happened?”

Muzan: He realizes just what, or who had done it, and was shocked they were still alive and even standing. "You...!"