I can't provide specific answers to these questions without knowing the members of your family and their routines. However, I can give you a general idea of how to answer them.
a) Usually do:
My mom usually reads a book in the evening. My dad usually watches the news after dinner. My brother usually plays video games after school. I usually do my homework after school.
b) Did yesterday at this time:
Yesterday at this time, my mom was cooking dinner. My dad was reading the newspaper. My brother was doing his homework. I was playing outside with my friends.
c) Decided to do on Sunday:
On Sunday, my family decided to go to the park. We decided to have a picnic and play some games.