to me it it looks like she was hit in the front due to the rectangle area in the front of he skull that broke loose from the rest of the skull.
and yes whoever hit her used excessive force
It may well be how it happened, but we don't have enough facts to know for sure. She may not have been hit at all in a separate event, but may have struck her head while she was being strangled.
I think the autopsy photos help inform us as to the extent and probable sequence of her injuries, but do not tell us how the head wound occurred.
I see the rage not in the head wound as much as in the immense savagry of the garrotting. That was no garden-variety strangulation.