Here is my code :Details are at the end

//================================================

#include "FS.h"
#include <SD.h>
#include <SPI.h>
#include <DHT.h>
#define DHTPIN D2
#define DHTTYPE DHT11
DHT dht(DHTPIN, DHTTYPE);
const int CS_PIN=D8;
void setup() {
pinMode(CS_PIN,OUTPUT);
Serial.begin(9600);
Serial.print("Inicializando o cartão SD...");
dht.begin();

if (!SD.begin(CS_PIN)) {
Serial.println("Falha, verifique se o cartão está presente.");
//programa encerrrado
return;
}

Serial.println("Cartão inicializado.");

}

void loop() {
float Humidity = dht.readHumidity();
Serial.print("Humidity: ");
Serial.println(Humidity);
float temperature = dht.readTemperature();
Serial.print("Temperature: ");
Serial.println(temperature);

File dataFile = SD.open("LOG.txt", FILE_WRITE);

if (dataFile) {
Serial.println("writing data in DS file LOG.txt");
dataFile.print(Humidity);
dataFile.print(" | ");
dataFile.println(temperature);
dataFile.close();
}

else {
Serial.println("error opening file");
}
delay(2000);
}

//================================================

Sample output on the serial monitor:

Humidity: 64.00
Temperature: 24.00
error opening file
Humidity: 64.00
Temperature: 24.00
error opening file
Humidity: 64.00
Temperature: 24.00
error opening file

//@@@@@@@@@@@@@@@@@@@@@

I am using:

Micro SD Card Module  The micro SD card module has six pins:

VCC , GND ,MISO, MOSI, SCK, and SS

Connections used:

// PIN DEFINITIONS /////////////////////////////////////////////

//

SD_SCK_PIN  connects to ESP8266 NodeMCU  pin D5

SD_MISO_PIN  connects to ESP8266 NodeMCU  pin D6

SD_MOSI_PIN  connects to ESP8266 NodeMCU pin D7

SD_CHIP_SELECT_PIN  connects to ESP8266 NodeMCU pin D8