I Dream of Murder

I had a really strange dream last night, and I thought that I should write it down, because I’m almost certain that it has some kind of deeper meaning (though I suppose all dreams do).
First of all, it was really complicated and kept shifting, so I’ll just record the main parts in order to avoid too much confusion.
It began with my whole family rollerblading in the streets of a city (I think it was St. Paul). I think that Dad and Amy were there, but I mainly remember Mom and Grandma E. (though Grandma wasn’t skating).
The funny thing was that we were rollerblading in the middle of winter; the streets were covered in slush and big snow banks separated the sidewalk from the road.
Anyway, Grandma E. and I decided to go back to the house, so I skated back beside her while she walked. When we arrived, I saw that the house was huge and Victorian-looking. At that point, I knew for some reason that my Grandma G. was about to be murdered inside.
I had this idea in my dream that she had died because she had gone to some sort of meeting (not a cult, but a domestic meeting like a sewing circle or something), and they had poisoned her so that when she got home she had a heart attack. I’m not sure why I was certain of this in the dream, because in real life I know that she died of cancer. Also, this dream involved some sort of time travel, because I was the age I am now, and I was going back in time to stop the murder that I knew had happened.
Meanwhile, I left Grandma E. outside the house on the sidewalk because I didn’t want her to get hurt. I entered the house. Inside were two women, a twelve-year-old girl (who was clearly in league with the women), and my Grandma G. The women and the girl had cruel, sinister looks about them, and I knew in the dream that they were really going to hurt my Grandma G.
Grandma G. was sitting on a chair chatting (I don’t think she had any idea what was going on) with one woman and the girl, and I sat down across from the third woman, who glared at me suspiciously. I remember that I sneakily took a large, serrated knife from the table and slipped it in my pocket in case I needed a weapon.
The woman sitting at the table must have seen me take the knife, because immediately she and the other woman jumped up and brandished knives at Grandma G. and I. We were backed into a corner, and they started slashing at us. I stood in front of Grandma G. and slashed back. The interesting thing was that no one got seriously wounded; we all simply made shallow scars on each other’s arms and faces with the knives.
While the fight was happening, the girl kept trying to offer Grandma G. something to drink, and I kept pushing her back because I knew that the drink was poisoned.
Finally we managed to get out of there unscathed, and met Grandma E. on the front walk.
In the road in front of the house the three appeared again, but this time the girl was trying to get Grandma G. to eat chewable Tylenol (which was also poisoned). I kept her away, and we all escaped down the road.