My mom passed away 1 year ago and since her death my dad has been seeing dogs at night.A couple of times he has seen my mom but mostly he sees 2 black dogs. He is awake when he sees these dogs.Why does he see them?

Maybe there was something about Dogs that was special with him and his wife. It could be her way of letting him know she is around. Some spirits leave pennies around, some it is a scent or a number.

There are different folklores about seeing black dogs after someone has died.
Folklores tend to fall in the same category as old wives tales though and most can be taken with a grain of salt.