Threeve is always a good place to start!!!
JK.......You've worked for them before, so perhaps explain to them exactly what you did here. Tell them about the situation with child, and how much you'd love to be part of their team again etc.......
As a headhunter in my previous life, the guy who speaks first loses. Make them say a number......then don't knee jerk react. Thank them and ask for a little time to consider - perhaps set a time to speak again. Consider what they've offered and decide if you should push for more or are happy to be back!!!
Good Luck!