For more pure education value, I would suggest that you teach C alongside a computer architecture course. In that way, a student comes to an understanding of what the hardware is doing at a fairly low level of abstraction, and how to control it using a language that's not far removed.
I would not suggest C++ simply because it's so big, and effectively crams multiple different languages into a single syntax. Perhaps as a 3rd year elective?
Similarly, I'd suggest either Scala or Haskell (or Scheme) to give them experience with something other than a procedural / object-oriented paradigm.
None of this will directly help them get a job, although it will be of ongoing benefit to their eventual employers for the duration of their careers.
If your institution's focus is more on training for employment, then Java, JavaScript and/or Swift are probably better options to add to their skillset, alongside Python and Go.
Yes, of course, Java, C# and C++ are here for decades to come, but a few weeks of nights and weekends at home or a couple of online courses will pick up their syntax if the student has had a sufficiently broad background.