/usr/lib/mono/4.5/Microsoft.VisualC.dll is in libmono-microsoft-visualc10.0-cil 3.2.8+dfsg-4ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/mono/4.5/../gac/Microsoft.VisualC/0.0.0.0__b03f5f7f11d50a3a/Microsoft.VisualC.dll