Dream about the deceased (Kind of long)?

Hi, my Nana passed away last July. It was my first family death I've ever experienced, and I took it horribly. Her and I were very very very very close. She was like my best friend. I've had 2 dreams about her though.. and I have no idea why. My mom said if you have a dream about a person that is passed, that you can't see their face in the dream. But in my dreams, I saw her face. My first dream happened about 3 months after she passed. We were at the church we go to, just standing on the stairs, then she just fell and I ran down to help her and she didn't wake up. The next dream was a few months ago. (It's very weird - just a heads up) My father and I were at a graveyard and my Nana was hurried there, but it wasn't the actual one she was really hurried in. We were just visiting her grave (it was night time) and then all of a sudden a man just pops out of nowhere and starts digging up her grave. He ran away with her body in his mouth and I just laid on the ground and started to cry, then my dad disappeared. Then a holagram of her poped up but it didn't say anything. I'm terrified that somethings wrong or its a sign that something bad is going to happen. Please help!