try below query
SELECT O.QUARRY, SUM(I.M2) AS INBOUND_TOTAL, SUM(I.Qantity_of_Case) AS TOTAL_CASE
FROM PRODUCTS U, QUARRY O, INBOUT I
WHERE U.PRODUCT_ID=OT.PRODUCT_ID AND O.QUARRY_ID=U.QUARRY_ID
AND MONTH(I.PRODUCTION_DATE)=5 AND YEAR(I.PRODUCTION_DATE)=2012
GROUP BY O.QUARRY
union
SELECT O.QUARRY, SUM(OT.M2) AS INBOUND_TOTAL, SUM(OT.Qantity_of_Case) AS TOTAL_CASE
FROM PRODUCTS U, QUARRY O, OUTBOUND OT
WHERE U.PRODUCT_ID=OT.PRODUCT_ID AND O.QUARRY_ID=U.QUARRY_ID
AND MONTH(OT.DELIVERY_DATE)=5 AND YEAR(OT.DELIVERY_DATE)=2012
GROUP BY O.QUARRY