I am so sorry to hear what happened!
For cleaning the mould off, use anti bacterial wipes and wipe over the ponies. It should come off without problems, and should kill it off
they have worked for me on furry mould, white mould, Brown mould, and black mould (don’t know what the types are actually called). I haven’t had it come back on anyone I’ve cleaned up. For their hair, give it a wash with washing up liquid/dish soap (also antibacterial) and then condition it to soften it back up
All the best, and sagain, sorry to hear this happened
Sunsparkle x