Question

A. When her husband is in town, is there no prohibition of seclusion at all (that is, the prohibition was never stated in such a case), or is there in principle a prohibition, but the fact that her husband is in town permits it? A possible practical difference would be whether there is any point in being stringent when her husband is in town or not.
B. How does the Rabbi explain the prohibition against two women (even apparently respectable women) being secluded with one man, as opposed to two men, who are forbidden to be secluded with one woman? In other words, does the Rabbi understand this as Rashi explains it—that women are more easily seduced, unlike men?