Hi guys.... Firstly, I am very dubious about anything like those scrolls that you need to purchase to provide the golden answer. I think you may find that Easom will be of English derivation (not Scottish!)
There are many variants, my surname is Eason.My gg grandfather was Easom, Other common spellings of my family name are Esam, Eashem & Easum. There is no relationship to the surname Isham or Isom as these are pronounced eye-som. Unfortunately, I cant shed any further light on the history of the Easom surname. I have ancestors named Esam in Cornwell UK back to the 1600's.
Some people believe that Easom is a variation of Eason. The derivation of which is Esne - son, son of sevant!!
Ofcourse nothing can be proven as the name & its spelling changes with the level of literacy of those recording it!!!