To dream of a vault, denotes bereavement and other misfortune.
To see a vault for valuables, signifies your fortune will surprise many, as your circumstances will appear to be meagre.
To see the doors of a vault open, implies loss and treachery of people whom you trust.
If you dream of seeing or buying a burial vault you will suffer the loss of someone close to you and/or some other sad loss.
To dream of a safe type vault holding valuables is a warning to guard your own wealth against those who would steal from you, or cheat you in some manner.
A vault hanging open with valuables inside warns you not to expose your wealth to everyone.