Something like this happened to me too.

in December of 2015 I had a really traumatic experience at home where I lived with my parents, sister and great grandparents. Basically my great granddad had some issues and got angry really quickly, he was very much the patriarch of the family, so said December he snapped over something minor like a water-heater argument with my dad (this happened every few years where he would snap, tear the whole family almost apart, got distant family members involved and then everything got back to normal eventually). So I lived my whole life in fear of an argument escalating again, so did my parents, which was a strain on my mental health and everyone was very cautious around my great granddad. Long story short, all of December 2015 was probably the worst time of my life. My great grandpa got so angry about the water heater thing, he hit my mom several times, threatened to burn down the house, threatened to kill himself and my great grandma almost every single day (we had to hide all of his knifes and meds so he wouldn't do anything) and he said things to all of us I can't even repeat because they were so hurtful and horrible. At one point I thought my great grandma was about to die, she was laying in my arms pretty much unconscious (until the ambulance came) and my great grandpa screamed at me that it was all my fault and he hated me all my life, so he was happy to be dead soon. All this and worse went on until Christmas Eve of 2015, when distant relatives (who still think everything is my moms fault because my great grandpa told them so) picked them up and I never saw both of my great grandparents again.

During this month or so I had several severe traumatic experiences, this mentioned above was only scratching the surface of what really went on. So when they were gone, I developed severe ptsd and needed lots of therapy to get myself together again. I had dreams almost every night about my great grandparents and seeing them again, I woke up crying almost every single night. I was pretty much raised by them and despite everything, them being gone so suddenly and not getting any closure made me even more upset. I loved them like my parents so I was not fully understanding the situation and why they were gone after 18 years of living in our house.

So every single night I would have some similar dreams, it would either be about being reunited with them and then something would tear us apart again or it would be about my great granddad coming to kill us all in different ways, every night I woke up in tears

This went on for months, until I had this dream. In that dream my great granddad was sitting in our dining room, hands on the table welcoming me in. He told me that everything would be okay and he was so sorry for what he had caused. The feeling og this dream was nothing like I ever had before. It was strangely familiar but also it felt really good in my heart to be with him again. He took my hand and held it and we both cried until I woke up in tears again, but this time it felt like a weight had been lifted off my sholders. I felt strangely okay again, which hadn't happened for months. The next day I found out that my great grandpa had died in his sleep. Even though I do not believe in anything remotely spiritual, I kind of kept thinking that he visited me in my dream one last time to try to fix something I guess. Or it just was a coincidence, anyway the recurring nightmares stopped that night and I am way better ever since.

Sorry for the long story, it is probably very confusing because there is so much more to it and I've tried to make it short, but it felt good to finally get this dream off my chest.