if your talking about a house like this...then, you pose a good question...
i used to live in a pretty big apartment complex, and always wondered where the safest place really was...
considering you has a tornado about EF-2/EF-3 strength, and it hit a two story home...it might destroy the top layers and partially collapse the building...and if you were in the basement, or interior room inside a 2-story or better house...you could risk being buried alive, or worse...
i always wondered about if you were trapped in the basement, and your water-main to your water heater broke...if there was no way to cut it off, you might even drown...or if the gas mane broke, or wires snipped...you could possibly burn to death trapped in a fire...
alot of that might depend on the angle which the tornado hit you, and the intensity and structural design...ill tell you one thing though...i wouldent want to be in any house when a big tornado was heading for it...
i dont know if i answered your question...but, personally i wouldent go to the basement...IMO the best defense against severe storms is being aware of the threat and keeping in eye on the location of the storms, and warnings...and if its headed your way, and you know what your doing...do your best to get away from the area before it comes...