Yes and no... The manner in which triggers are defined in XLSForm means that no, you cannot have a dependent question being 'triggered' by anything other than a change in a single so-called antecedent question [aside, I discuss this limitation, albeit in a difference context, in some detail here: Spec proposal: expose xforms-value-changed event with odk:setgeopoint action in XLSForm]. Which is to say, Question B can only be 'triggered' by a change in Question A, not as you say a change in Question A or C.
However, under the covers in raw XForms, there is actually nothing to prevent you performing multiple xforms-value-changed event triggered setvalue actions - which is bascially what an XLSForm trigger becomes - to accomplish this. That is, you can actually have Question B be recalculated whenever Question A changes or when Question C changes (in fact they can even perform completely different calculations!)
Have a play with this XForm. It essentially consists of two different types of multi-triggers. The first triggers the same calculation whenever either of two antecedent questions change; basically your "trigger can't be an or expression" situation. The second set is a min/max example that readjusts a previously entered value should the min or max then be adjusted.
MultiTriggers.xml (2.3 KB)
I'm not 100% sure of your specific usecase around restoring original images, but - at least in terms of being able to have an or expression of some form as a trigger - perhaps this could be helpful?