。
She mistook me for Tamori.
Literal
She [topic-は] me [object-を] Tamori-san [as-と] mistook.
The frame Xを Yと間違える ('mistake X for Y') gets a celebrity-lookalike twist here. タモリ (Tamori) is a hugely famous Japanese TV personality — black sunglasses, deadpan delivery, host of the long-running noontime variety show 笑っていいとも! (1982–2014) and the geography/history program ブラタモリ. The さん attached gives the level of polite reference natural for a public figure, even one being mistaken for. A built-in cultural reference that lands instantly for any Japanese reader.