Without any knowledge of the strangers, this is an easy question to answer, I'd save the people closest to me, because I actually have a connection with them and they feature in my life.
What would happen if you changed the 100 strangers to all women and children? Or if one family member from each of the 100 hundred was forced to watch a screen of their loved ones trapped in a room as a faceless individual decides to gas them. What if it was 99 randoms and your mum, with the 10 other closest people in the other room. What if one room contained your family, the other your friends?
Every situation is subjective, someone who doesn't like their family or who has a shitty family would choose their friends.
Personally, if my dog were still alive and the choice was between 100 strangers and her, I'd save her everytime, but if the choice was 10 of my friends against 100 children, I would probably save the 100. Odd how our minds work isn't it?