Looking at how GOLD is coded as HOME:
G→H(+1)
O→O(no change)
L→M(+1)
D→E(+1)
The rule is: every consonant shifts forward by 1, while vowels stay the same.
Applying the same pattern to SONS:
S→consonant→S+1=T
O→vowel→O+0=O
N→consonant→N+1=O
S→consonant→S+1=T
Therefore, SONS is coded as TOOT.