Dollop is definitely a reasonable answer if you want less than a "normal" amount of cream on your strawberries, especially compared to "oodles" or "lashings" (which both imply you want a lot more than would be normal).
A dash is a reasonable amount for hot sauce, a spice, or maybe sugar with strawberries.
But for cream + strawberries, a dash would be too little and maybe nearly pointless. You'd barely taste it, like maybe be enough to get a few of them damp. That seems nearly pointless to me; if you don't like cream then just ask to not have any, but I'm lucky that I don't have to mess around with tiny servings to stay healthy. Maybe you could get some flavour out of a dash of cream on a couple strawberries. (And I like milk, cream, and dairy in general, so maybe I'm just having a hard time imagining liking only a small amount of cream more.)
Of course, given that we're talking about cream, you'd probably end up with an amount at the lower end of what's reasonable, rather than any specific quantity like 1/8th of a teaspoon. i.e. "a dash of cream" will be lot more volume than "a dash of hot sauce" when you're talking to another human, not a robot strictly applying a definition of a dash.
So on second though, a dash is a reasonable answer, too.
A dollop could definitely imply you want less than is normally served, but it's pretty subjective so you'd probably want to say "only a dollop" to get about enough cream to get the strawberries wet but not have much excess liquid in your bowl.
This answer doesn't really have a strong point one way or the other, but hopefully it gives some insight into the subjective implications of the words. Or makes you want some berries + cream. Going to get some now (blueberries + raspberries).