What should I do regarding my aunt and her husband's request for the photos I took at my aunt's wedding, which include pictures of the family's women, knowing that the agreement was for the photos to remain with me, and I fear that my aunt's husband might see these photos containing women who are unlawful for him to see, and I am afraid of betraying the trust placed in me by the family's women?

If the photos contain women who are not mahram (definition) to your maternal uncle-in-law (husband of your maternal aunt), then do not give them to him and apologize, because it is not permissible in Sharia (definition) for men to view photos of non-mahram women, especially if they did not consent to being photographed, unless the photos will remain in your possession and no non-mahram man will view them.