Web Service to retrive files inside folders in SharePoint Library

Requirement: Get reference of files inside folders in SharePoint Library using List Web Service.I have multiple files inside ChildSourceFolder” folder.

Environment:SharePoint 2013

Folder Structure:

SourcePath: DocumentLibraryName/ParentFolder/ChildSourceFolder/FileName.docx

Issue: I am not able to get the value of source file path and source file name inside the folder structure.

          I need help in caml  query to build proper query option to get the reference to the source file.

 ///called function

 ///<example>

 ///webServiceURL=”https://siteurl:9000”

 ///sourceLibrary=”MyDocumentLibrary”

 ///sourceFolderPath=”ParentFolder/ChildSourceFolder/”

 ///</example>

public System.Xml.XmlNode GetItemsfromLibrary(string webServiceURL,string sourceLibrary,string sourceFolderPath){           

   ListWebServiceReference.Lists objListService =new ListWebServiceReference.Lists();

   objListService.Url = webServiceURL + "/_vti_bin/Lists.asmx";

   objListService.Credentials = System.Net.CredentialCache.DefaultCredentials;

try {

 System.Xml.XmlDocument xdListData =new System.Xml.XmlDocument();

 System.Xml.XmlNode xnQuery = xdListData.CreateElement("Query");

 System.Xml.XmlNode xnViewFields = xdListData.CreateElement("ViewFields");

 System.Xml.XmlNode xnQueryOptions = xdListData.CreateElement("QueryOptions");

 xnQuery.InnerXml = "";

 xnViewFields.InnerXml = "";               

   //I need help to build proper Query Option. I am not able to get file names and file path               

    xnQueryOptions.InnerXml = ????;

    //something like below code

    // xnQueryOptions.InnerXml = "<Folder>"+ sourceFolderPath + "</Folder>"; 

System.Xml.XmlNode items;

if (String.IsNullOrEmpty(sourceFolderPath))

   items = objListService.GetListItems(sourceLibrary, string.Empty, xnQuery,xnViewFields,string.Empty,null,null);

else

   items = objListService.GetListItems(sourceLibrary, string.Empty, xnQuery,xnViewFields,string.Empty,xnQueryOptions,null);             

 return items;             

}

 catch(Exception ex) {returnnull;}          

}

 ///calling function

System.Xml.XmlNode xnListData = GetItemsfromLibrary(webServiceURL,sourceLibrary,sourceFolderPath);

XmlNodeList oNodes = xnListData.ChildNodes;

foreach (XmlNode node in oNodes)

 {

 XmlNodeReader objReader =newXmlNodeReader(node);

  while (objReader.Read())

     {

      if (objReader["ows_EncodedAbsUrl"] != null&& objReader["ows_LinkFilename"] != null)

         {

            sourcePath = objReader["ows_EncodedAbsUrl"].ToString();

            sourceFileName = objReader["ows_LinkFilename"].ToString();

         //call other function

         //pass sourcePath andsourceFileName as parameter, but I am not able to get the value of these parameter

         }

      }

  }