12 years in the White House, if you count the time her husband served as VP for Reagan.
yes and no, the VP and wife don’t live in the White House, they live some distance away in DC. The VP has an office in the West Wing of the WH, but I don’t think the wife of the VP spends a lot of time in the WH except during certain state and ceremonial functions. So Barbara Bush would have had primarily the 4 yrs. Jan. 1989 to Jan. 1993 in the White House.
20 if you count her son’s time. She may not have lived there when W was the president but I guarantee she was a presence.