I still am having troubles getting things to add up here. If there were no leaves, the dormant oil shouldn't have hurt the tree. HOWEVER, I don't know what caterpillars would have been doing on a tree with no leaves (unless there was a tree over/around it in leaf?). And if there were trees in leaves, why were they using dormant oil???
ALSO, what is the mold you mentioned in your first post? Is it a saprophytic growth on dead tissue? A lichen that might be totally innocuous? Could there be another tree around that has an aphid problem with heavy honeydew that created a sooty mold problem...which may be unrelated to the maple problem.
Pictures would be really helpful.
From your posts, I am thinking the tree STILL doesn't have any leaves? Have your parents check the stem tissue for green cambium to see if there is still life there.
If this tree died, it may have succumbed to something other than the spraying. So for the time being, try to keep an open mind.
Sylvia