Ответ:
b. She lives in Philadelphia and works in a cafe in the centre of the city.
c. She has been working(Present perfect continuous)there for 3 years.
Т.е. "Она работает здесь 3 года" действие началось, но не закончилось. Но если надо только из перечисленных времен,то She has worked there for 3 years, но первый вариант правильный.
d. At the moment her best friend from England is staying with her.
e. She enjoys her holiday very much.
f. They have already visited many museums together and they were to the theatre three times