John Snr. may have died by 1861 (would explain why there is only one child showing for them). This looks like Margaret and son John in 1861:
Margaret Wilson 40, head, laundress, b. Tarves Aberdeenshire
John Wilson 11, son, b. Inverury, Aberdeenshire
James Law 28, lodger, joiner, b. Culsalmond
Address: New Street, Kintore, Aberdeenshire
Regards.
Monica