You cannot get the text node by Selenium. Please try the workaround with JS below:
IWebElement span = driver.FindElement(By.Id("lblName"));
IWebElement div = span.FindElement(By.XPath(".."));
string script = "var nodes = arguments[0].childNodes;" +
"var text = '';" +
"for (var i = 0; i < nodes.length; i++) {" +
" if (nodes[i].nodeType == Node.TEXT_NODE) {" +
" text += nodes[i].textContent;" +
" }" +
"}" +
"return text;";
string text = driver.GetJavaScriptExecutor().ExecuteScript(script, div).ToString();