There is absoulutely no question that the second amendment guarantees citizens their right to own and carry guns for self defense, not only at home, but on the streets.
The second amendment specifically prohibits any gun law that would infringe on the right to bear arms, and since DC is no state, there is no legal justification for any gun law in Washington DC.
When the founding fathers wrote the constitution, and debated the second ammendment, they did mention, and all agreed, that guns “could” be also used for personal self defense(against attackers - white or indian), as a third, and minor, reason for why we have the right to bear arms.
Tom Jefferson, for a good example, commonly carried 2 flintlock pistols when he walked the streets of Washington DC. They are beautiful pistols, I have seen photographs of them.
“Arms in the hands of citizens [may] be used at individual discretion… in private self-defense…”
– John Adams, 2nd Pres. of the USA:
John Adams, A Defense of the Constitutions of the Government of the UAS, 471 1788
“Laws that forbid the carrying of arms… serve rather to encourage than to prevent homicides, for an unarmed man may be attacked with greater confidence than an armed man.”
– Thomas Jefferson, Quoting 18th cent. criminologist Cesare Beccaria, 1764
“A strong body makes the mind strong. …I advise the gun. While this gives moderate exercise to the body, it gives boldness, enterprise, and independence to the mind…Let your gun therefore be the constant companion of your walks”
Thomas Jefferson
“I ask, Sir, what is the militia? It is the whole people, except for a few public officials.”
– George Mason, 3 Elliott, Debates at 425-426
“The right of self-defense is the first law of nature. In most governments it has been the study of rulers to confine this right within the narrowest limits possible. Whenever standing armies are kept up, and the right of the people to keep and bear arms is, under any color or pretext whatsoever, prohibited; liberty, if not already annihilated, is on the brink of destruction.”
– Justice George Tucker, Virginia Supreme Court, 1803