Please explain about that And I need one word of that.
'Caregiver'. A (primary) caregiver is the person who takes primary responsibility for someone who cannot care fully for himself or herself, such as a child. However, the term is more often used for people looking after the old or infirm.
Why I recommend these words:
The word "babysitter" is used to call a person that takes of children or babies temporarily.
The word "nanny" is used to call a person that takes of children or babies for a long period of time; let's say maybe 40 hours per week.