I would definately look into at least those. You should probably try and take some time to look into databases and SQL as well. I would recommend going to a site like W3Schools and going through as much as you have the time for (although their tutorials aren't always the best, you can at least get a good idea of what's out there). The more you know, the better your chances will be right?
As a web developer, I suggest learning about the server-side scripting mentioned in the above reply. If the company you're going to intern at is a company that develops websites that utilizes changing content similar to forums, news websites, or social media websites, there's a very good chance you will run into php or asp.net. Research the companies you're planning on applying to. Sometimes you can find out what other skills from their website or HR person.
Good luck in your internship search. Keep learning new skills and continue to hone your previously learned skills.
Yes, you must learn PHP. If you want to go completely in the web developing then you must be well versed with any one of the programming language like PHP, Java or .Net. And amongst these I think PHP is best now a days. It is also simple and is widely used.
Best of luch for your internship.