To dream of a vault indicates a threat against your wealth and financial stability. There are people around you that may attempt to use charm or fraud to take it from you. It may also indicate your inner 'safe,' or the place where you keep your inner potential. When you dream of the safe, you need to consider looking at your true potential and putting it to good use.
To see an open vault is an indication that you may be rubbing your money in the noses of others.
To see a burial vault represents the personal sadness and grief you have experienced as a loved one passed away.