Issue is that SQL query syntax needs to escape single quote, which is done by using two single quotes:
' (in John's) needs to become '' in SQL syntax
I think easiest way is to split out the search term into a variable:
qry_item_value = "John's Cabin"
qry_item_value_fixed = qry_item_value.replace("'", "''")
qry = "Item_Name = '%s'" % qry_item_value_fixed