I really like the second one! I think you can really expand on that well and bring in how you learned to empathize with someone very different than you.
1) mistrust of others is not a cultural trait. Also, it focuses on your grandparent, not on you.
2) it showed you can work to help people different from you but it might not address a prompt that may want more about your life experiences contributing to diversity.
Most advice to applicants focuses on the personal statement and description of work or activities required to complete the initial centralized application