Answer:
Comparative: Jane walked more softly than Judy
Comparative: Jane walked softlier than Judy
Superlative: Jane walked the softliest
Superlative: Jane walked the most softly
Step-by-step explanation:
Comparative: more softly or softlier
Superlative: most softly or softliest
However, more/most softly is used more often than softlier/softliest in everyday conversation. If you can only choose one option for comparative and superlative, I think you should use more/most softly.