It makes me sad almost nobody mentions Perl and/or Perl6 (they are essentially entirely different languages, but designed by the same guy, so I'd say they follow similar design methodology). Although it is not as popular as it used to be, Perl is still extremely useful, and I found that the community around the language is by far the best and most welcoming to newcomers. Also a lot of people will say that Python is superior due to its readability, concise formatting etc., and indeed there are areas in which Python would be the better choice (machine learning and statistics to name a few) but for a quick file processing, OS admin tasks, or a simple multi-threaded web scraper, Perl would be my first choice. And I find that due to the flexibility and TMTOWTDI motto, I find the language much more expressive and I feel more creative writing Perl code. But I wouldn't dwell too much on picking the right scripting language, Python, Ruby, or Lua are all fine choices.
For lower level stuff and performance, definitely C++ and then eventually if you need it C as well, but I think it doesn't make much sense the other way round.
And as already said in this thread, it's good to pick up a functional language, just to broaden your horizon if nothing else.
First off, obviously there isn't really a clear black/white answer to this. Secondly even security is such a broad field that it really depends on your focus (a similar question could be what programming languages/technologies are the best for web development, where you'd get answers ranging from classic LAMP stack, to Node.js, python, RoR, Angular and many others, and it depends on whether you want to do front-end, back-end, both or whatever combination). So firstly I'd say it's important to pin-point what you are personally interested in; I'd say that if you want to be working on some "serious" exploits in widely used software, you are looking at C and Assembly, and C++. Obviously for web hacking, you'd be looking more at scripting languages, both in terms of their usages as the underlying technologies, as well as to automate those mundane repetitive tasks, so PHP, ASP, Perl, Python, Bash scripting etc. is something to look into.
But you should also be well versed in sys-admin tasks, things like maintenance, event logging, filesystems and permissions... And lastly there is networking and all the issues and things associated with it, tcp/ip stack, routing and so much more.
The thing is, working in security isn't really dependant on the programming languages you know, either what will matter is your specialization (if you have any), or the overall skillset that you can offer to the company (if you can secure a web application on a shared host, but don't do anything about file permissions and other settings on the server, either someone else needs to do it, or the security of the webapp is pretty useless); be aware that you will be (or should be) learning something all the time, again depending on your interests, and at the same time you have to stay on top of news in research and exploits, so in a way it's really tough but also very interesting.
For lower level stuff and performance, definitely C++ and then eventually if you need it C as well, but I think it doesn't make much sense the other way round.
And as already said in this thread, it's good to pick up a functional language, just to broaden your horizon if nothing else.