Seeing dead relatives in dreams

Hii xx My nan died a week ago and last night I dreamt about her. I've never really been sure if I believe in life after death, but was this really her ? The first dream: me and my grandad (her husband) were in their bedroom in their house, talking and sorting through stuff. He went out of the room for a moment and she appeared over the other side of the room. She started going through her old clothes. I ran up behind her and she turned around. She wasn't frail and ill like she was for the last years of her life, she was younger and could walk. She knew where she was and what she was doing, which she hadnt for a while because she had Alzheimer's when she was alive. I rushed because I felt as though she could only stay for a short while. I asked her how she was and she told me she was much happier now. Later on that night I had a second dream, more of a nightmare: I started getting messages on my phone from my nan ( despite her not knowing even what texting is ) i got the messages one after the other, constantly. I didn't want to look at the messages because I was scared. I did get a quick glance at the messages though and they said things like 'help me' etc. I was aware in this dream, like the other one, that she was dead. After a couple of mins of receiving the messages, I got my mum to take my phone from me. Any insight greatly appreciated xx