Partial panel, using the turn coordinator, ASI, DI and VSI. Partial panel work is hard especially if you are out of practice and a vacuum failure so low would have made it hard work to transition to partial panel quickly and effectivly.
It pays to practice partial panel skills frequently if you are instrument flying.
It could well have been the case that this person was not in practice and the failure so soon after take off overtook him with fatal results.
As I recall there was a very similar case in the UK a year or so ago that was put down to the same problem. Vacuum failure on take off and the pilot was unable to control the aircraft and crashed.