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Although the Lewis and Clark expedition ended on September 23, 1806, Meriwether Lewis and William Clark remained close both personally and professionally up until the death of Meriwether Lewis on October 11, 1809.
Lewis, Clark and Clark's wife Julia actually lived together for a short time (ca. 1808) in St. Louis, Missouri. Julia Clark gave birth to a son in January of 1809, the baby was actually named Meriwether Lewis Clark.
In August of 1809, Meriwether Lewis left for Federal City (Washington D.C.) William Clark also left for Federal City, but stopped off in Kentucky to visit relatives first. William Clark actually received news of Meriwether Lewis death en route to Federal City via a Frankfort, Kentucky newspaper article.
As fragile as Meriwether Lewis mental state was at the time, he knew that William Clark was en route to Federal City. In the dillusional state that he was in before his death, there is a high probability that Meriwether Lewis believed he had reached his destination instead of actually being in Tennessee.
To answer the question, Yes. Meriwether Lewis did have reason to believe that William Clark was coming to see him.