You may be able to claim your dad as a Qualified Relative dependent subject to the below rules
They don't have to be related to you (despite the name).
They aren't claimed as a dependent by someone else.
They are a U.S. citizen, resident alien, national, or a Canadian or Mexican resident.
They aren’t filing a joint return with their spouse.
They lived with you the entire year.
They made less than $4,050 in 2017. (Social Security income generally does not count)
You provided more than half of their financial support