This page of our guide to Psychonauts 2 lists the Memory Vaults available in Hollis' Hot Streak.
There is only a single Memory Vault found in this level.
Breaking Dr. Potts
Location: Doctors Only.
In the morgue you'll have several areas to choose from. Go into the "Doctors Only". There aren't any missions there, but you can find a pickup. Simply turn left and you'll see the secret. This is the only Memory Vault in this location.