Answer:
Otto Frank was the father of Anne Frank and Margot Frank. Otto Frank was the only survivor of the family. He was a spice businessman so he used to travel a lot.
Otto Frank and his family tried to move to the United States but it was taking too long and at that time world war II started which had made things worse.
Otto frank tries to escape from Cuba but Germany revoked the nationality of the Jews living outside of the country which leads to the cancellation of the immigration application.
These were the scenarios that lead to the delay in taking his family out of Europe.