IMO, The discipline policy is irrelevant here since it was your child's recurring behavioral issue, not hers. Giving the tax form W-10 and statement of account at termination is pretty standard. The bite was not witnessed or treated so she is not wrong in her feelings even if you feel you are not at fault. I would try to remain humble and not be defensive when she comes to pick-up her child's belonging. Hopefully, it will be a quick handoff.
