Compare multiple columns (column A,column B,Column C) and return value (Column D)

I have two sheets (Sheet1 and Sheet2) with columns A,B,C,D (as example given below)

I need two compare as follows ...
Column A of Sheet1 with column A of Sheet2
Column B of Sheet1 with column B of Sheet2
Column C of Sheet1 with column C of Sheet2
(Column C is DATE .. I just need to compare month for month, Not considering the day. I.e i need to Ignore (day))
And return value in column D.

Please see below table for reference

SHEET1
POS NAME DATE SN
1 rim 11-Feb-13 RA001
1 tyre 18-Jul-13 TA007
2 brake 20-Sep-13 CB898
2 head 26-May-13 HI345
1 tyre 31-Jul-13 RA009
2 rim 1-Sep-13 TC078
1 brake 5-Jun-13 TF157


SHEET2
POS NAME DATE SN
2 head May-13
1 tyre Jul-13
2 rim Sep-13
1 brake Jun-13
1 rim Feb-13
1 tyre Jul-13
2 brake Sep-13

There are n number of rows... table given above is just for reference.

Thanks in advance

I could not properly tabulate it