To spew advice at you in relation to my own family's experience with a recent death:

First, I only a couple of months ago lost my father-in-law to cancer. We had 3 years of knowing it was coming, 1 month of hospital, and then 3 days of hospice. I can tell you with even all of that time, there is no closure to the poor parenting my husband experienced. And that was nothing compared to your abuse. Dad spent a lot of that three years telling my husband "I love you" but no deep conversations ever happened. Husband says it wouldn't have meant anything since Dad was just scared he was going to die. Do not expect closure.

Secondly, the period when we knew death was imminent, that last month, was very intense emotionally. Husband found it exhausting. He dreaded going to the hospital. I stayed nights with dad (He and I got along great) so husband could feel less guilty about ditching and a least have a stand-in. The period of hospice, where dad was conscious but only minimally response, and everyone kept having good-bye conversations with him, were emotionally devastating to husband. What did he have to say except to tell a dying man how things went wrong...and who wants to do that to their dying dad? Do not go see her. It will be way too intense and miserable.

Third, I can say that people did skype with him. He did respond to that. If you decide to make contact, that is a good choice. Much better than paying money to fly, and then being stuck there.

Finally, and not relevant to this: These people are your abusers, not your family. It can help clarify things if you think of them with that correct term, rather than the false ones of 'Mom" "dad" and "sister". They never acted properly as a mom, dad or sister. Should you be worried about the immortal soul of your abuser? Maybe, in a kind, generous Christian who worries about everyone' soul kind of way. Should you buy a plane ticket to go say goodbye to your abuser? Nope. Do you owe your abusers anything at all? Nope. (but it's still emotionally devastating, isn't it? You deserved better. I'm so sorry. Internet hugs)