<img src="/Employee/ShowImage/<%=Model.EmployeeID%>" alt="Фото" />

[HandleError]
public class EmployeeController : Controller
{
    public FileContentResult ShowImage(int id)
    {
        string emptypath = HttpContext.Server.MapPath("~/Content/Images/ImageNotFound.jpg");
        var image = Db.Employees.Where(d => d.EmployeeID == id).Select(d => new { d.Photo, d.PhotoPath }).SingleOrDefault();
        byte[] imageData = image != null && image.Photo != null ? image.Photo.ToArray() : System.IO.File.ReadAllBytes(emptypath);
        string filename = image != null && image.Photo != null ? GetFileName(image.PhotoPath) : emptypath;
        return File(imageData, GetContentType(filename), filename);
    }
}

<a href="/Employee/ShowImage/<%=Model.EmployeeID%>">Файл</a>

return File(imageData, GetContentType(filename), filename);