In Anne Frank's diary, she doesn't use Miep's real name. She refers to her as "Mrs. Kraler," a pseudonym that is meant to protect Miep's identity.
Miep Gies played a crucial role in the Frank family's survival during their time hiding. She provided them with food, supplies, and information, and she helped keep their secret.
After the Frank family was arrested, Miep was instrumental in recovering Anne's diary, which she eventually gave to Otto Frank, the only member of the family to survive the Holocaust.