A couple things are important to bring up Prudence.
1.You have to read the art museum magazine in Joanna's office which tells about Prudence.
2. You have to look at the plaque outside of Joanna's office and click on the one about Prudence so that Nancy makes a statement about her being on the board or donating or something like that.
If you have done those things and can talk with Rose, he should bring up Prudence. Have you started the activities in the Temple?