Mount Tamborine has a number of bush walking tracks. I believe Cedar Creek Fall Track is the easiest one. All path are paved concrete. That is very very easy to access. That is not oblique at all. Included returned time, the whole track can be completed within an hour. That is very suitable for your whole family.
Moreover, at the end of this track, there is a small fall and a water pool. That looks cool! The scenery can make you enjoyable for a while.
If you bring your family to visit Mount Tamborine, you can drive to Cedar Creek Fall and have a enjoyable walk in there.