Jane Austen was the first of these great women writers. She produced six completed novels, all of which deal with the problems and limitations of women's choices. At this time, the only respectable career for a woman was to marry, so the dilemma of her heroines' was also to marry but for love. Her most popular novel has always been Pride and Prejudice.
What does the underlined sentence mean?
I don't think it is phrased very well. It would be better expressed as "the dilemma facing her heroines was whether to marry for love or for money". As the writer says, respectable women in Jane Austen's time were expected to get married, since they had no real means of supporting themselves independently. A dilemma is a situation requiring a choice between equally undesirable alternatives, so they might find themselves having to choose between a penniless man whom they loved, or a rich man whom they did not love.
I'm not a teacher of English, but I have spoken it for (almost) all of my life....