The water runs down the inside wallof the garage. The outer wall of the mobile home. How do I fix this?

It's the actual roof that is leaking the water down inside the garage's outer wall. What kind of roof does this mobile home have? If it is shingle then I would definitely suggest that you (or someone you trust) go up and physically investigate the roof's condition looking for loose shingles or any vent or standpipe that is not properly sealed with roof tar. Sometimes roofs will be fine for years and then start leaking at areas where the flashing has shrunken due to age.

Also, recaulk or retar the area where the garage meets the home. That material too could have shrunken over the years.

Without a physical inspection it's hard to properly diagnose. If the home's roof is intact, then it's definitely the connection spot where the garage meets the house.