I don't have a direct answer for you, but a workaround would be to install a launcher like Kids Place, which has parental control and can lock the child out of various apps or services.
Set up Multi User and put her on the second account, then yeah use a kid mode apk. The new Tab 4 may be offering kids mode standard instead of as a separate OS build. You could ask over at XDA if anyone has flashed Kids Mode OS onto a stock wifi model.