Is it permissible for a woman who prayed to Allah to avert marriage from her, for the sake of her sister who was experiencing a delay in her menstrual cycle, to now pray for a righteous husband after her sister has reached menopause?

It is permissible to supplicate to Allah to grant you a righteous husband. You erred, however, in supplicating against yourself, for the Prophet, peace and blessings be upon him, forbade that. As narrated by Muslim from the Prophet, peace and blessings be upon him: "Do not supplicate against yourselves, nor against your children, nor against your wealth, lest you coincide with a moment when Allah grants a request and He responds to you." And: "Do not supplicate against yourselves except for good, for indeed the angels say 'Amin' to what you say." Also, Muslim narrated from Anas that the Messenger of Allah, peace and blessings be upon him, visited a man and asked him: "Were you supplicating for anything, or asking Him for it?" He said: "Yes, I used to say: 'O Allah, whatever punishment You will inflict upon me in the Hereafter, hasten it for me in this world.'" The Messenger of Allah, peace and blessings be upon him, said: "Subhan Allah! You cannot bear it, or you are not able to bear it. Why did you not say: 'O Allah, grant us good in this world, and good in the Hereafter, and protect us from the torment of the Fire'?" So he supplicated to Allah for him, and He cured him.