We have a lot of similar questions on the site already, such as this one, although that doesn't mention the longer zoom. The answer here really depends on what you want to do, which is a bit hard because you are just starting out. There is no one right "general purpose" answer, because what people do generally varies so much. Both lenses give you a different kind of versatility — the 55-250 for its telephoto reach and obvious zoom range, while the 50mm gives you very high image quality for the price and a wide aperture.
I personally don't own any lenses beyond 135mm, and don't miss them. (In fact, the 135mm is a manual lens I rarely even use; 77mm is my typical portrait lens.) But that would probably sound crazy to someone else. So, if you have to make this decision, think about how you already take photos and what you want to do. If you like to stand far away from the action and still get up-close photos, you might start with the zoom. If, on the other hand, you like to take portraits, the 50mm will probably suit you better. (On an APS-C camera like the Canon you are considering, 50mm makes a nice portrait length.) And the 50mm f/1.8 is noticeably more useful in low light.
You may also want to consider a prime lens in the 28mm to 35mm range — this is the very versatile "normal" focal length for this camera. See Why do people recommend 50mm or other prime lenses as starting lenses for learning photography? for some discussion on 35mm vs. 50mm on APS-C. Unfortunately, I don't think Canon offers a cheap entry-level lens in this range (unlike Pentax, Sony, or Nikon). There is a 40mm f/2.8, which I would actually strongly consider — see Which lens serves best as the only lens on a cropped body for a beginner: the 40mm f2.8 or 50mm f1.8? for some views on that.