{new Date(moment().subtract(120, 'years').format('YYYY-MM-DD'))} code example
Example: moment diff
var a = moment([2007, 0, 29]);
var b = moment([2007, 0, 28]);
a.diff(b, 'days') // 1
var a = moment([2007, 0, 29]);
var b = moment([2007, 0, 28]);
a.diff(b, 'days') // 1