I would say it depends on your reaction. If you know you will be a calming influence then your horse will be reassured by your prescence and will take comfort from your confidence that all is well. If, on the other hand, you are liable to fret, fret at home, your horse will pick up on your anxiety. Either way, make everything as normal as possible as changes to familiar routines can cause more stress than the fireworks!
The best thing is to have a confident, unbothered horse nearby that she can take a lead from. Be there for a while, but don't over fuss - not reacting is the best way to show her there is nothing to worry about..