Thanks to Srikanth Kasturi. PDFSharp code worked fine for me. Here is the code.

using PdfSharp.Pdf;
using PdfSharp.Drawing;

TiffImageSplitter tiff = new TiffImageSplitter(); 

 public void tiff2PDF(string fileName)
        {
            PdfDocument doc = new PdfDocument();

            int pageCount = tiff.getPageCount(fileName);

            for (int i = 0; i < pageCount; i++)
            {
                PdfPage page = new PdfPage();
                
                Image tiffImg = tiff.getTiffImage(fileName, i);
                
                XImage img = XImage.FromGdiPlusImage(tiffImg);
                
                page.Width = img.PointWidth;
                page.Height = img.PointHeight;
                doc.Pages.Add(page);
               
                XGraphics xgr = XGraphics.FromPdfPage(doc.Pages[i]);

                xgr.DrawImage(img, 0, 0);
            }

            doc.Save("C:/CJT/PDF/34326.pdf");

            doc.Close();
            
        }

 To make this work you need Tiff related code also. Here is the Tiff Image Splitter code.

 class TiffImageSplitter
    {
        // Retrive PageCount of a multi-page tiff image
        public int getPageCount(String fileName)
        {
            int pageCount = -1;
            try
            {
                Image img = Bitmap.FromFile(fileName);
                pageCount = img.GetFrameCount(FrameDimension.Page);
                img.Dispose();

            }
            catch (Exception ex)
            {
                pageCount = 0;
            }
            return pageCount;
        }

        public int getPageCount(Image img)
        {
            int pageCount = -1;
            try
            {
                pageCount = img.GetFrameCount(FrameDimension.Page);
            }
            catch (Exception ex)
            {
                pageCount = 0;                
            }
            return pageCount;
        }

// Retrive a specific Page from a multi-page tiff image
        public Image getTiffImage(String sourceFile, int pageNumber)
        {
            Image returnImage = null;

            try
            {
                Image sourceIamge = Bitmap.FromFile(sourceFile);
                returnImage = getTiffImage(sourceIamge, pageNumber);
                sourceIamge.Dispose();
            }
            catch (Exception ex)
            {
                returnImage = null;                
            }

            //       String splittedImageSavePath = "X:\\CJT\\CJT-Docs\\CJT-Images\\result001.tif";
            //       returnImage.Save(splittedImageSavePath);

            return returnImage;
        }

        public Image getTiffImage(Image sourceImage, int pageNumber)
        {
            MemoryStream ms = null;
            Image returnImage = null;

            try
            {
                ms = new MemoryStream();
                Guid objGuid = sourceImage.FrameDimensionsList[0];
                FrameDimension objDimension = new FrameDimension(objGuid);
                sourceImage.SelectActiveFrame(objDimension, pageNumber);
                sourceImage.Save(ms, ImageFormat.Tiff);
                returnImage = Image.FromStream(ms);
            }
            catch (Exception ex)
            {
                returnImage = null;                   
            }
            return returnImage;
        }

} 

Hope this helps.