"I said I would do it, and I did it because if there is anything new, which is unlikely after the eight prior investigations that have been held, we should know about it because the point is, what are we going to do to both honor the people that we lost and try to make sure this doesn't happen again?" Clinton said.
After the 11-hour hearing, Clinton told Maddow that she invited her team back to her house for Indian food and drinks.
"We do want to have a good conversation where people come to the table ready to actually learn about what we can do," she said. "I'm afraid that's not necessarily what this particular committee is doing, but we have learned a lot from our previous investigations, and I'm certainly committed to doing all I can to make sure we do save lives."
Clinton said the lack of bipartisanship between Democrats and Republicans blocks progress from being made.
"We've gotta break the stranglehold that the extremist views in the Republican Party have on too many people who are otherwise sensible and try to get them back into the pragmatic problem-solving that should be the hallmark of the relationship between the president and the Congress," she said.
Clinton had warm words for Vice President Joe Biden, who announced this week he wouldn't seek the White House.
"I am a huge Joe Biden admirer, friend, a former colleague, and I know this was an excruciating decision in a time of just such pain and grief for him and his family," Clinton said. "He is liberated and I don't think history is done with him. There is a lot for him and the President to keep doing in the next year and a half."
She added, "I want to build on the progress that they are leaving behind. I feel very strongly about that. I want to go further, but I think the real point of this election is whether or not the Republicans are going to be able to turn the clock back and rip away the progress that has been made."
Clinton also defended her husband's legacy on social issues, including gay rights, that are now under fire from progressives as she seeks to capture the Democratic nomination for president. She explained her involvement in shaping certain policies, including increases in criminal incarceration and the Defense of Marriage Act that were enacted in the 1990s.
"On Defense of Marriage, I think what my husband believed -- and there was certainly evidence to support it -- is that there was enough political momentum to amend the Constitution of the United States of America, and that there had to be some way to stop that," Clinton said.
"And there wasn't any rational argument -- because I was in on some of those discussions, on both "don't ask, don't tell" and on -- on DOMA, where both the president, his advisers and, occasionally, I, would chime in and talk about, "You can't be serious. You can't be serious." But they were. And so, in a lot of ways, DOMA was a line that was drawn that was to prevent going further."
While Clinton said some of President Bill Clinton's policies that increased incarceration were in response to "horrific crime rates," she told Maddow they "went too far."
"First speech I gave in this campaign was about mass incarceration, and about reform of policing practices. And I think that sometimes, as a leader in a democracy, you are confronted with two bad choices," she said. "And it is not an easy position to be in, and you have to try to think, OK, what is the least bad choice?"