I am the doing the cake for my grandmother birthday. The party is 2 hrs from my house. I am better to stack and then when I get there to put on the flowers or put all together at the party? For the cake it's self, should probly keep on cake board that will fit it and then onceat the party place it on the bigger fondant covered one. I was thinking putting it in my trunk, but there one steep hill and too woirred about cake shifting in my trunk.

The answer probably will depend partly on the size of the cake(s). The smaller the tiers, the more chance of problems if it is already stacked.
I have delivered stacked wedding cakes that far w/o problems, but have also have a couple of problems.
It probably would be easier on your nerves to take the tiers seperately and stack once at the venue. Just give yourself extra time (arriving early) as it might take longer than you think to put it together.

SPS! I recently delivered a five-tier cake down the roughest road in the county with no shifting whatsoever.

The two tier will be the small the med paisley set. Or would be safter with doing double barrel cake?