Don't worry about invisibility, unless I know the situation before hand, this is what I would pick for my menu abilities.
Menu C
1) Concussion (Ps) :The astral construct can manifest concussion blast (manifester level 7th) as a free action once per round. (free actions are fun)
2) Blindsight (Ex) The astral construct has blindsight out to 60 feet. (since I don't know the situation before hand, and I may have an invisibile attacker)
For my 3rd Menu C ability I trade out it for 2 Menu B abilities
Menu B
3a) Improved Fly (Ex) The astral construct has physical wings and a fly speed of 40 feet (average). (flight is fun, and drastically reduces the number of things that can affect my astral construct at level 6)
3b) Improved Grab (Ex) To use this ability, the construct must hit with its slam attack. A construct can use this ability only on a target that is at least one size smaller than itself. (affects creatures of size large or smaller, use that +38 grapple score to your advantage and attack at the same time.)