So, even after being asked, you never looked it up. I see.
According to Politifact's fact checker, there is a hierarchy of persons involved in the security of the Capitol. There is a
sergeants-at-
arms for the House and one for the Senate. The Sergeant-at-Arms for the senate reported (at the time) to Chuck Schumer, and the Sergeant-at-Arms for the House reported (at the time) to Nancy Pelosi (which I stated in my post). The Sergeants-at-Arms are members of the Capitol Police (which I stated).
Twice, prior to January 6, President Trump informed Nancy Pelosi that he heard there was going to be a large crowd gathering in Washington and offered the National Guard for protection. Twice. He needed to make that offer, and he did. Twice. Nancy Pelosi and the Sergeant-at-Arms refused citing "optics". We see what happened. Was she solely responsible, no. That's ludicrous, but had she accepted the National Guard when it was offered, this would not have happened.
No, US Capitol security is not only Pelosi’s responsibility
I mistakenly implied that she, alone was in charge of Capitol security, and that was an error. She is part of the security hierarchy and as such, had the right to accept use of the National Guard when it was offered.