What does this creepy dream mean?

I was at my grandparents house and apparently there were zombies. No explanation to how but people were being killed and coming back as monsters. I walked over across the street and went into a house. There was nobody in there but I was looking for someone. I don't know who but apparently I was looking for someone I knew. Someone walked in with me but they got attacked and I ran out of the house. I fell into a hole and found myself inside some underground complex. I was walking around and a group of people were helping me but I don't know who they are. Two stay with me while the others go off to hold back the dead people from getting in. I ran away into another area with the help of two others. I walked out a door and found myself in my own neighborhood, which was odd because I fell into the hole by my grandparents house. I walked into a church people were praying that it would end, they wanted to be saved. Some of them looked at me while I walked around. I turned around and walked out of the church and I found myself inside a large prison/jail. The prisoners were actually kind of nice. It was like a community that had survived. Someone gave me some beef jerky and for some reason I paid him in a small chunk of coal, which made him very happy, like coal was valuable to him or something. I walked up to some lady at a front desk that had become like a store or something. I turned away and walked along the wall. Suddenly I couldn't see anything other than darkness. I saw a dim light and saw the heads of 5 or more aliens(those tall alien grays with slits for mouths and big black eyes) I became aware that it was a dream and they tried to come closer to me, and I felt like they wanted to do harm to me but they couldn't because some force was holding them back. I slowly woke up.