。
She thinks money and happiness are the same thing.
Literal
She [topic-は] money and happiness [topic-は] same [quotative-と] is-thinking.
Two layered topic-は markers: the outer 彼女は frames the whole sentence as about her, and the inner 金と幸福は frames the equation as the topic of her thought. と here serves two roles in close succession: first to coordinate two nouns ('money AND happiness'), then to mark the quoted content ('that they are the same'). 思っている ('is thinking, currently believes') as a resulting state captures the held belief rather than a passing thought.