Metropolitan Police said Janice Nix has been charged after Andrea Bernard died following an assault in south London.
Nix, of Clapham southwest London, was also charged with child cruelty in relation to offences towards another child, who was aged eight at the time.
It is reported Andrea was assaulted at an address in Thornton Heath, south London, on 6 June 1978.
Andrea and Nix were known to each other, the Met Police has said.
She was hospitalised and initially treated in Croydon, before being transferred to a specialist burns unit in East Grinstead, West Sussex.
