Bemusement is the noun: the state of being puzzled, and the look that shows it. You meet it in a few set shapes. "To my bemusement, …" opens a sentence about something that surprised and puzzled you. "With bemusement" and "in bemusement" describe how someone watched or listened. And it often follows a look or an expression: "a look of bemusement crossed his face." Because it is a noun, it can be counted like a substance rather than an event — you have some bemusement, not a bemusement. Like the rest of this family it is formal and written; a Taiwanese student is far more likely to need it for reading than for speaking. And like the rest of the family, it carries a light touch — bemusement is a mild, sometimes half-amused puzzlement, not distress. If someone is genuinely lost and worried, the word you want is confusion.