The parameter "Correction_Comments" from your function is not used at all within the function. Instead, there is a variable "MSAGSTREETNAME", a local variable that is not referenced elsewhere. In addition, the if statement is using an assignment (=) rather than a test (==).
if streetnamefield == 'HEMLOCK':
return 'IN PARCEL 103'
This will pass the field
Correction_Comments into your
Reclass function. You may instead want to run this in the Field Calculator for the
Correction_Comments field, against the
MGAGSTREETNAME field e.g. right click
Correction_Comments, Field Calculator, and run with