I'm with the minority opinion (again). Your friend was ungracious and inhospitable, and for her to be huffy over your apology is churlish.
Your child made a mess in her bathroom. You did your best to clean it and her up, and your hostess continued finishing the job off.
You said goodbye and left, obviously embarrassed.
If I had been the hostess I'd be thinking about how awkward you must be feeling and trying to make you feel better.
In fact someone visiting my house once changed their baby on our changing table, said baby then proceeded to expel liquid poo at great velocity over the opposite wall, which then flowed rapidly downwards, over the skirting and onto the carpet. Baby continued to loudly and explosively projectile poo faster than she could wipe / attempt to put on new nappy. She didn't know what to do first and was clearly mortified.
I laughed, helped her sort out the baby first, took the wipes out of her hands and finished the cleanup myself.
And although our newly painted nursery wall was never the same, I wouldn't have done anything to make her feel worse than she already did. Poor woman!