Obviously a mother does not hit the question of how she reached her age without acquiring responsibilities by the simple expedinent of acquiring them. . . which, come to think of it, means the question needs to be narrowed down a bit. The elderly can also go on adventures. A woman who has successfully launched her children has carried out her responsibilities and is free for new ones to come down the pike. At that, you might get away with a mother whose children are almost launched, because they are old enough to be part of the adventure. It's the youngsters who are the problem.
Because children, as mothers can tell you, keep you awfully busy. It can be really interesting to finesse it. . . err. . . 'scuse me. (scuttles off to count.). Erm. It's so interesting that I've only done it three times (plus one father). But then, in "Sword and Shadow", not only does the mother have servants, she also faces a peril that comes into her home; in "Witch-Prince Ways", the peril is that she has to rescue her baby; in "Fever and Snow", the baby is likewise central to what the father has to do; only in Madeleine and the Mists is there the matter of juggling one and then two children about the adventures, even with servants. (And of course, the first three are shorter.)
And all four of them were shaped and limited by what the characters could not do because they had responsibilities toward a child.