It is important to realise that in Mrs. Ramsay, Virginia Woolf is capturing an impression of women that is characteristic of Mrs. Ramsay's older generation where women naturally felt themselves to be inferior to the men they were married to and thought that they offered little to the world. This of course creates an interesting tension between the younger generation of women, such as Mrs. Ramsay's daughters and Lily Brescoe, who definitely do not agree with such patriarchal assumptions. However, for Mrs. Ramsay, everything is really very simple, as the following quote suggests:
Indeed, she had the whole of the other sex under her protection; for reasons she could not explain, for their chivalry and valour, for the fact that they negotiated treaties, ruled India, controlled finance; finally for an attitude towards herself which no woman could fail to feel or to find agreeable, something trustful, childlike, reverential; which an old woman could take from a young man without loss of dignity, and woe betide the girl—pray Heaven it was none of her daughters!—who did not feel the worth of it, and all that it implied, to the marrow of her bones!
Mrs. Ramsay therefore believes that men are worthy of her protection and regard because they control the world and because they act in a chivalrous way towards women. That is enough, in her mind, to warrant her subservient attitude towards them and to support her belief that they need her protection and service. Mrs. Ramsay is therefore a character who captures a certain set of beliefs about gender and marriage that is particular to a certain generation. The more traditional approach of Mrs. Ramsay is therefore juxtaposed with the more "modern" approach of other female characters.