Help with photo restoring

Hey everyone, I need some help,

I have a very old photo of my Grandpa, Mom and Grandmother, 

I have tried everything i could to restore this photo (Honestly dont know what i am doing, nor do i know how to restore a photo). I was wondering if someone here could PLEASE, PLEASE (I am begging here)

help me with this photo.. I want to restore the photo and give it to my mother, for a birthday present. this is seriously the last photo she has of her Dad and it would make her day. Her mom (my grandma) passed away in 2006. all photos of my mothers dad (my grandpa) are gone, and my mother only has this photo.

and my mother, has been wanting someone to restore the photo for a very long time. 

if someone here could please help me! i would truly from the bottom of my heart, truly would appericate it..