She went to the museum by taxi.

Literal

She [topic-は] museum [as far as-まで] taxi [by-で] went.

Two distinct prepositions in this short sentence. まで marks the endpoint of motion ('as far as'); で marks the means of transport ('by taxi'). タクシー is a katakana loanword from English. Note the contrast まで vs に on 博物館 — まで emphasizes the journey's endpoint, where に would just mark the destination plainly.