What will i expect in court when i go and change my daughters last name to my last name

It is completely possible to do that. If your partner is dead or if you are divorced then you can change your daughters name.

A name chnage for a juvenile is basically the same as an adult. You have to notify her father and he has a right to protest, if he does the court will decide. If you have a good reason to do so, the court will allow the name change.
Good cause would be
parent is a criminal serving a very long term and society makes it hard on the child as the name is recognizable in your community
the father is deceased ; though in some state relative sban protest especially of it is the deceased only male progeney
Father has physically, ifnancially, and emotionally abandoned the child and his whereabouts are unknown
Father has been convicted for crimes upon children or his child

Reasons such as that are persuasive to the court
y