Good job on the ID's, I agree. Don't know what happened to them. The euonymous is generally a very tough hardy plant that you have to restrain from taking over your yard.
It would help if you would tell us where you are located, what your weather/climate has been like, and whatever you can about what has happened to them - are they in sun or shade, how do you water/ fertilize, etc, did they get sick suddenly or has it been going on for a long time, whatever you know about what your soil is like.
The better information you give us, the better help we can be.