Ugh, that sounds beyond upsetting, especially on top of the emergency with your mom. Best wishes for her recovery.

As far as the ants go, since they came from your friend's place and you've cleaned them out as well as you could, there probably isn't a huge breeding colony waiting to return. I would just put out a little ant trap somewhere near Kaa's enclosure so they have an alternative destination if a few stragglers show up.

Breathe. You didn't do this to her, and you're taking the steps to make it right.