。
She acts innocent in front of everyone.
Literal
She [topic-は] anyone [genitive-の] front [at-で][even-も] innocent imitation [object-を] does.
うぶなまねをする is a productive frame: [na-adjective]+な+まねをする means 'pretend to be / act like X / put on a (X) front.' The same shape powers 馬鹿なまねをする ('act foolish'), 子どもじみたまねをする ('act childish'). うぶ ('naive, innocent, inexperienced — especially in love or worldly matters') is itself a colorful word with a softer, almost affectionate flavor. The combination implies a calculated performance — pretending to be more naive than she actually is.