Help using index and match to find value based on 3 criteria

calof1 

The logic is bit unclear. You have 3 criteria - Scenario, Stock Code and Year. In source data you have no combination Stock Code=FXL and Year=1, however in answers you suggest 5% for Year=2. Why?

If ignore above formula could be

=IFERROR(
    INDEX($C$12:$S$15,
        MATCH(1,INDEX(($C$12:$C$15=C$4)*($D$12:$D$15=$C$3),0),0),
        MATCH(TRUE,ISNUMBER(SEARCH($C$2,$C$10:$S$10)),0)),
"N/A")

Couple of more comments. Your file is practically not downloadable, perhaps due to comma in name - not all system support it.

I'd recommend not to use Merging Cells. Potentially you will have lot of issues continue using merging. Alternative is - select sequential horizontal cells and apply Center Across Selection