Question

passive to active sentence of a party is being held tonight at his house by his friend

Answer 1

His friend is holding a part at his house tonight.

Answer 2

Given sentence:
A party is being held tonight at his house by his friend.

Active voice of the given sentence:

His friend is holding a party tonight at his house.

Additional information:
Active voice - A type of sentence where in the subject of the sentence precede the object of the sentence.

Passive voice - A type of sentence wherein the object of the sentence precede the subject of the sentence.