It looks like two different issues are overlapping, which is not uncommon. The branch dieback in shrub dogwood species tends to be due to canker, and a common culprit is Botryosphaeria canker. (Although the linked page focuses on Rhododendron, this fungus can attack a wide range of species.) Drought stress can be a typical precursor to infection, as shrubby dogwood species tend to be not highly tolerant of drought and prefer even soil moisture. Disease symptoms and progression can lag behind when the stress occurred, though, so it can be hard to tell when an infection began. Last summer, much of Maryland experienced drought, as with this year thus far. To best determine when shrubs need water, you can feel the soil about six inches deep in the root zone. If somewhat dry to the touch at that depth, a thorough watering is probably needed; if damp instead, watering can probably wait. The linked page provides more guidance.

The wilting is due to branch death or under-watering, but the leaf spot damage could be fungal or bacterial. (It's hard to tell from photos, but we're leaning towards bacterial in this case.) "Leaf spot" diseases can be quite common on dogwoods, especially in years with wetter spring weather, as we had this year. Fungicide cannot cure existing disease (and few can affect bacterial pathogens), and we seldom recommend their use because of other ecological impacts they may have.

You can keep cutting back (as close to the ground as possible) any dead stems (those becoming black- or dark brown-barked is a telltale sign), plus rake-up and dispose of any fallen leaves (between now and autumn) to dispose of them, as this may reduce the infectious spore abundance for next spring.

The elderberry may just be drought-stressed, as they too prefer even soil moisture levels; they can also get spider mite outbreaks (many plants are right now, due to the heat and lack of regular rains) that might be contributing to premature leaf drop.

Miri