I don't think any of the languages you've mentioned are ones people would consider one of those "vogue" kiddie languages. Scala, D, Swift, Everything on this list, is not something I would tell a child to start learning, and then bet a career on.
That said, use the right tool for the job! PHP is absolutely a great idea for a webpage, which is, by it's very nature, a scripted entity. With much pain, C *can* do it, but there is a better tool, already. PHP - and just about every other scripted language is written in C/C++. So is the JVM. It's all just (another) layer of abstraction, in the end.
But, when it comes to kernels, firmware, and just about anything embedded - C should be near the top of your list. It's not the most popular language, but it's steady. It sits nicely on top of only assembly language - and thus, is easily used on any (and almost every) hardware-architecture there is.