Steroid is contraindicated in –
here: -Topical corticosteroids enhance fungal replication and corneal invasion and therefore, contraindicated in a fungal corneal ulcer.
Now, option 'a' requires specific mention here:-
Topical corticosteroids are contraindicated in herpetic keratitis. But not in all forms of herpetic keratitis :-


Epithelial herpetic keratitis (Dendritic ulcer, geographic ulcer) → Topicla corticosteroids are contraindicated.
Stromal keratitis (Disciform & Diffuse necrotic) → Topical corticosteroids along with topical antiviral drugs are used as the first line of treatment.


So, my opinion for this type of question is that :-

i) If herpetic keratitis has given as the option, then look at other options. If any of the other options is a clear cut contraindication for corticosteroid (e.g. fungal corneal ulcer in this question), consider that option as your answer. If no ther option is a contraindication for topical corticosteroid, consider herpetic keratitis as the answer.
ii) If examiner has specifically mentioned dendritic ulcer as an option, consider it as the answer.
Herpes keratitis
Atropic dermatitis
Fungal corneal ulcer
Exposure keratitis