Best case scenario for school district:
Prove via FBI or forensic information security audit team that there was no monitoring software of any kind, no remote monitoring, no logging. Prove that the assistant principal did not know what he/she was talking about when she was directly questioned by the parent.
Prove there was no conspiracy to monitor students in their bedrooms. Prove (this is hard) that the assistant principal obtained the incriminating photo by illegally searching their hard drive. Provide settlement in six figures with half of proceeds going to subsidize free laptop program for inner city Philadelphia.
Put assistant principal on leave, supply black electrical tape fee-free, remove any Remote Desktop capabilities in the OS. Hold press conference with state attorney general in two weeks to jointly demonstrate total innocence.
Worst case: TV crews camped out on Lower Merion High School campus for weeks.