This means that when she died, she fell on the floor in front of Peter. This expression should not be confused with falling down at a person's feet as a sign of humility.
Here "breathed his last" means "breathed her final breath" and is a polite way of saying "she died." See how you translated a similar phrase in [Acts 5:5](../05/05.md). (See: [[rc://en/ta/man/jit/figs-euphemism]])