Question

I think that your brother has a nicer smile than _____. Which pronoun correctly completes the elliptical clause?

A. him

B. them

C. he

Answer 1

A.  Him 

B is incorrect and C is also incorrect .

Answer 2

Hello there!
The only word that fits here is the word Him. 

I think that your brother has a nicer smile than him. 
Hope i helped today!
~Sammy)