Barbara.... 9:30 pm is not "night" over here :))))) Keep in mind many stores close between 8:30 and 9:30, therefore, there're plenty of people around. Not counting also those going out for dinner, of course.
Besides, Barcelona is a safe city -generally speaking- if compared to many other Western cities its size. Still, as in any city, basic precautions are always in order. If you're a savvy aware traveller you know what I'm talking about.
While I generally agree with the good advice of fellow Barcelonian Carlos, in this one I don't as you wouldn't have to be near the area I presume Carlos is thinking about -which is in the "lower" side of El Raval. In fact, you'd be walking by Pintor Fortuny street to go to your hotel, which is an OK street to walk: http://bit.ly/2R9p9Yz Honestly, you'll see for yourself, it's far easier than taking a cab. Metro is out of the question cause you'd be wasting a long time for such a short distance.
Furthermore, if you're talking about a Fri or Sat, then is "safer" than ever as lots of Barcelonans (really, lots!) go out for dinner/clubbing, etc.
Enjoy!