Writting one page diary entry such as i could imagine Mrs bennet would have written after she returned from the ball

Sorry, we can't do writing assignments on this short answer forum.

But how i can find such a good answer for it?

I gather you are asked to write a one page diary from the point of view of Mrs. Bennet. There is no set answer to this. You must consider Mrs. Bennet's personality and how she would react to the ball.