At the end of Mansfield Park, Fanny's virtues of constancy, patience, kindness, self-discipline, and integrity are rewarded in a variety of ways. First, she is welcomed back to Mansfield Park with open arms and deep appreciation by Sir Thomas and Lady Bertram, having earned their love and esteem. Second, she is able to bring her sister Susan back with her to Mansfield Park to replace her as a companion to Lady Bertram. Third, her enemy, the evil and spiteful Mrs. Norris, is banished from the family home and sent into exile with the spoiled Maria. Fourth, she is able to rest assured that Edmund will not marry the morally unsuitable Mary Crawford. Fifth, she escapes Henry Crawford. As the narration tells us in the novel's last chapter,

My Fanny ... must have been a happy creature in spite of all that she felt, or thought she felt, for the distress of those around her. She had sources of delight that must force their way. She was returned to Mansfield Park, she was useful, she was beloved ...

Finally, and most importantly, Fanny wins the love of Edmund, who finally proposes to her. The two marry, promising Fanny long-term happiness and prosperity. As Austen's narrator states,

With so much true merit and true love, and no want of fortune and friends, the happiness of the married cousins [Fanny and Edmund] must appear as secure as earthly happiness can be.