Answer:
She has bought a house.
Step-by-step explanation:
Active voice is when the subject does the action and acting it out. It is different from a passive voice in that the subject is not acted upon by the verb and that the subject comes before the verb in the sentence.
In the sentence "A house has been bought by her," the subject "her" is places much after the action "bought". This makes it a passive voice. And so, to make it into an active voice, the subject will come before the verb, with a change in the pronoun "she" instead of "her". And the object will be at the end of the sentence.
Thus, the final sentence in the active voice will become-
"She has bought a house."