Serial monitor doesn't work with piezo buzzer
Pin D10 of NodeMcu is io 1 which is RX pin of Serial interface of the esp8266. Serial is on NodeMCU connected to USB. The pin is on board labeled RX.

D8 is boot config pin io 15. It must have pulldown on board. The pulldown can disturb the input on this pin. Use D6 (io 12) as echoPin.