Bittrich's II SS Pz Korps (9th and 10th SS Pz Div) was in the Arnhem/Einhoven area facing the Paratroops. His units were at Falaise and were regrouping in Holland. The 5th and 7th German Armies were also in the pocket, escaped and were sent to the German/Luxembourg area for refit. So they did not face Monty in operation Market-Garden.
Horrocks XXX Corp was facing the German 15th Armee which was in retreat from Normandy but not at Falaise. It was on the Channel coast at the time.
"The rout of the German forces in July and August led the Allies to believe that the German army was a spent force unable to reconstitute its shattered units, but all was not what it seemed. The failure of the 21st Army Group to clear or cut off the Scheldt from the mainland allowed the German 15th Army to move 86,000 men and 600 artillery pieces back into the mainland of the Netherlands, directly into the path of the planned attack. The arrival of Field Marshal Gerd von Rundstedt as Wehrmacht Commander-in-Chief West in early September also helped stabilise the German front. Rundstedt, who replaced Field Marshal Walter Model, was generally detested by Hitler, but well-respected by his troops, whom he had back in fighting condition within the week. Rundstedt immediately began to plan a defense against what Wehrmacht intelligence said was 60 Allied divisions at full strength.[1]
http://www.answers.com/topic/operation-market-garden-1