There is something wonderful ___ him.

The correct answer is -B

The presposition `About' is correct here.

Here `About' means in connection with.

The remaining options doesn't fits here.

Of- When we want to denote `Who /what does it belong to' ,what does it show.

Ex- A page of the book.

Inside - it is used when we want to say something/someone is in room or building.

Enclosed in a container,or space.

Ex- He was inside the building.

For - to indicate time(over a certain period of time), instead of,to indicate destination.

Ex- He was leaving for Pune tonight.