If you want to see where each of you are, and send messages in case you need help or to see if you're all OK, then Life360Life360 Family Locator is the free way to go.
For security, like locking phone, taking pictures, an all-in-one, then download AndroidLostAndroid Lost.
If you want to password protect your apps (e.g. connecting 4 dots), then so far I've been using Smart App Protector. If you know of a better app protector, please let me know.
Also, where can I find an iPhone app that can do the same secret things like AndroidLost? I am desperately looking for a free app that you can hide and access everything on it remotely either through mobile or PCSmart App Protector.