Yes diaper rash cream can be used for treating hemorrhoids.
If the diaper rash cream contains Zinc Oxide which most of the diaper rash creams do contain the diaper rash cream will treat hemorrhoids just like hemorrhoid cream will.
However diaper rash cream is not as good at treating hemorrhoids as hemorrhoid cream is but it will help treat it.
I have applied diaper rash cream to my hemorrhoids when I ran out of hemorrhoid cream and could not get any at the time.
It took a bit longer for the hemorrhoids to clear up using diaper rash cream but the diaper rash cream did work to get rid of the hemorrhoids.
Soaking in some apple cider vinegar bath water also helps hemorrhoids.
Just fill a bathtub with a few inches of warm water and then add some apple cider vinegar to the bath water and then soak in the tub for 30 minutes or so at a time.
That helped to clear up my hemorrhoids as well.