Ask if you can take it in advance?

Ask if you can take it on another day, if he refuses go up the chain.

Talk to the Dean and see if there's something you can't do to either take the final early, or provide proof of death (like a copy of the death certificate) so they know you're not lying and take your final later. Funerals are an important part of the grieving process, so if I were you, I wouldn't miss it. You can always retake the class, you cannot have another funeral. I'm very sorry for your loss, OP.

That's...some BS. Email your teacher, the department chair, dean, etc a copy of the obituary.

ask if you can do it sooner, don't miss her funeral

Drop the class and properly mourn your grandma. Bring able to complete the grieving process is more important than one dumb class.

Usually if you approach your professors and ask to take exams early, rather than late, they're willing to work with you.

Your professor can't fail you for a university-excused absence. Show him the obit/funeral schedule and ask if you can take it early. As another poster said, if he refuses absolutely take it up the chain of command. I'm so sorry for your loss, your grandmother must've been a wonderful person :(

Person :(

This is where you need to start taking it over professor head. Say I am prepared to take exam on such and such date before I leave for funeral but professor Brown is unwilling to work with me. Go to the department head, then keep working your way up to the Dean. Is there anybody in Student Services that can help you/ advocate for you?