While I do not speak for Dreamhost, I have had experience in cases such as this.
If the account was set up as a personal account then you have very little (if any) hope of gaining access to the account.
The company in question will need to see if they have any legal grounds to stand on, then seek the aid of a local authority.
If the company cannot gain access to the account, then they will need to see what (if any) backups were made and attempt to rebuild from there.
See Apple's case not so long ago, the family of a deceased iPad owner applied to Apple to gain access to the iPad, on the grounds that the account was a personal account and that the family were not the account owner, Apple refused and won the following court case.
This is a very good example of improper IT management, any accounts for a business need to be set up as such and any credentials used to access those accounts stored securely where multiple administrators have access to them.
Often the first thing I do when taking over a project or team, is to build solid documentation on everything, no matter how insignificant it might first appear to be.
Anecdotally, this is what Google refers to as "the bus factor", as in - How many people in conjunction with the project could be hit by a bus before the project is in serious trouble of falling apart. In this case, one.