When added to a person’s name, what does the suffix -ito(a) mean?

It refers to smaller sizes of youth, kinda like nino

When you use the suffix "-ito(a)", it's like saying "little ."
For example, saying "pobrecito" is like saying " poor little thing." 
For a name, it's kinda like a cutesy way of saying the name. :) For example, my name is Monica. But when my grandfather calls me "Moniquita", it's kinda like saying "little Monica." 

Espero que esto ayude!

The answer is a but you could also use c if you want