Your dad's mom just died. I don't care if you're over it or not. He needs you there. I think instinctively, you already know that you should be attending.
These statements constitute a great posting. This is why you go, Woz. No matter what your dad tells you, he wants you there, and he needs you there more than he is likely willing to admit to you or to himself. I'm sure he's proud of you and what you've done in your career, so he tells you he "understands" if you don't make it. But you absolutely have to set aside whatever "trouble" it is to go right now and do it. You didn't mention a grandfather so I am assuming he's dead, meaning your father just lost his last remaining parent. It actually makes my stomach hurt to think of you not going to support him and the rest of your family right now.
All valid points and yes my grandfather passed away like 20 years.
I wasn't trying to make this about my dad too much, but for general background my dad and I aren't terribly close either. He went through a very substantial mid-life crisis a dozen years ago and has to a significant extent stepped away from my immediate family (moved away, misses birthdays, won't him from him for months, ditches us on Christmas to go see the family of a woman he was dating, etc.). I say this only to clarify that being there would be for everyone on my dad's side of the family, including but not limited to my dad.
I'm thinking of calling my uncle, who of everyone on that side, I'm closest to. This is really starting to bother me a lot.