Meld Configuration with sourcetree

Install Meld > Add it to SystemPath where Meld.exe is located.

SourceTree > Tools > Options > Diff > Diff(Custom > Meld.ext) & Merge(Custom > Meld.exe)

Arguements:
Diff: $LOCAL $REMOTE
Merge: $LOCAL $BASE $REMOTE --auto-merge --output=$MERGED

If you got DLL Issue :
Copy "C:\Program Files (x86)\Meld\lib\libgirepository-1.0-1.dll" to "C:\Program Files (x86)\Meld\libgirepository-1.0-1.dll".
One Directory Up.