I've not tested Vista for this issue, but I will now.
*EDIT* Got the info you need.
Download the appropriate offline update for your computer...
Windows Vista DirectX 11 offline update for x86-based systems.
You must be registered to see the links
Windows Vista DirectX 11 offline update for x64-based systems.
You must be registered to see the links
x86 = 32-bit operating system
x64 = 64-bit operating system
To determine which architecture you're using...
1) Open Control Panel.
2) Click the "System" applet.
3) Under the "System" subheading, look at "System Type:" It will tell you if you're using a 32-bit or 64-bit operating system.
Restart your computer after you've installed the offline update and try playing MotH.
Please note: Extended support for Windows Vista ended on April 11, 2017. Which means there will no longer be system updates available for this OS.
Also, if you could, please let me know if this worked. Thank you!