Here's why:
* Caregiver: This is a broad term that encompasses anyone who provides care for another person, including children. It emphasizes the nurturing and supportive role of the person.
* Grandmother: While a grandmother often acts as a caregiver, it's a specific familial role.
Therefore, caregiver is the most suitable word to describe both a person who looks after young children and a grandmother, as it highlights the common element of providing care.