I’m so sorry to hear about the loss of your dad, your friend and your grandad - that is such a lot of grief to deal with in a short space of time. I’m sorry also to hear that you weren’t able to visit your grandad and that you feel he didn’t have dignity in his last months.
Anger can be a very common part of grief. It’s important to have people to talk to and somewhere to let those emotions out (even if that’s just writing them down here on this site), as bottling them up can make things worse.
While you wait for more replies to your post, here are some posts by others who’ve been through multiple losses - you might find it helpful to have a read and reply if you’d like to talk more to them:
@Cherry65 posted: So angery
@Mandie posted: Struggling to cope with loss
We have also had these recent posts from @daver about losing his best friend - Friend lost - and from @Sam1990 about losing their grandad -Loosing my Grandad.