help with "if" command

Guys, I have a problem in my project.

It is to measure the internal temperature with 3 sensor “Tmed” = ((t2 +t3 +t4)/3) average.
this value should be compared to the external temperature “t1”
if the difference of the average internal to external temperature “(tmed - t1)” is less than 10 °C
The buzzer should be activated
and the average humidity “hmed” is less than 50% the buzzer should be activated.

In this sketch can not trigger the buzzer … commands are right. I did another sketch with 2 DHT11 temperature variation and did and it worked perfect.
I think we’re having some conflict because this sketch the same command does not work.

#include <Wire.h>
#include <DHT.h>
#include <LiquidCrystal.h>
#define DHT1PIN 10 // Sensor externo 
#define DHT2PIN 12
#define DHT3PIN 9
#define DHT4PIN 8
#define DHTTYPE DHT11 // tipo de sensor DHT 11 
#define DS1307_ADDRESS 0x68
byte zero = 0x00; 
LiquidCrystal lcd(7, 6, 5, 4, 3, 2); 
                
DHT dht1(DHT1PIN, DHTTYPE); 
DHT dht2(DHT2PIN, DHTTYPE); 
DHT dht3(DHT3PIN, DHTTYPE);
DHT dht4(DHT4PIN, DHTTYPE);
void setup() {
  Wire.begin();
  Serial.begin(9600);
  lcd.begin(16, 2);
  dht1.begin(); 
  dht2.begin();
  dht3.begin();
  dht4.begin();
 pinMode(13,OUTPUT);  //Buzzer
  //setDateTime(); 
}
void loop() {
  printDate();
  printsensor();
}
void setDateTime(){
  byte second =      45; //0-59
  byte minute =      15; //0-59
  byte hour =        21; //0-23
  byte weekDay =     3; //1-7
  byte monthDay =    18; //1-31
  byte month =       10; //1-12
  byte year  =       14; //0-99
  Wire.beginTransmission(DS1307_ADDRESS);
  Wire.write(zero); //stop Oscillator
  Wire.write(decToBcd(second));
  Wire.write(decToBcd(minute));
  Wire.write(decToBcd(hour));
  Wire.write(decToBcd(weekDay));
  Wire.write(decToBcd(monthDay));
  Wire.write(decToBcd(month));
  Wire.write(decToBcd(year));
  Wire.write(zero); //start 
  Wire.endTransmission();
}
byte decToBcd(byte val){
// Convert normal decimal numbers to binary coded decimal
  return ( (val/10*16) + (val%10) );
}
byte bcdToDec(byte val)  {
// Convert binary coded decimal to normal decimal numbers
  return ( (val/16*10) + (val%16) );
}
void printDate(){
  // Reset the register pointer
  Wire.beginTransmission(DS1307_ADDRESS);
  Wire.write(zero);
  Wire.endTransmission();
  Wire.requestFrom(DS1307_ADDRESS, 7);
  int second = bcdToDec(Wire.read());
  int minute = bcdToDec(Wire.read());
  int hour = bcdToDec(Wire.read() & 0b111111); //24 hour time
  int weekDay = bcdToDec(Wire.read()); //0-6 -> sunday - Saturday
  int monthDay = bcdToDec(Wire.read());
  int month = bcdToDec(Wire.read());
  int year = bcdToDec(Wire.read());
  //print the date EG   3/1/11 23:59:59
  Serial.print(monthDay);
  Serial.print("/");
  Serial.print(month);
  Serial.print("/");
  Serial.print(year);
  Serial.print(" ");
  Serial.print(hour);
  Serial.print(":");
  Serial.print(minute);
  Serial.print(":");
  Serial.print(second);
}
void printsensor(){
  int h1 = dht1.readHumidity(); //umidade externa
  int t1 = dht1.readTemperature(); //temperatura externa
  int h2 = dht2.readHumidity(); 
  int t2 = dht2.readTemperature(); 
  int h3 = dht3.readHumidity(); 
  int t3 = dht3.readTemperature(); 
  int h4 = dht4.readHumidity(); 
  int t4 = dht4.readTemperature(); 
  int hmed = ((h2 + h3 + h4)/3); //average internal humidity
  int tmed = ((t2 + t3 + t4)/3); //average internal temperature
  int tdif = (tmed - t1); //diference internal temperature with external
  
  if (tdif<10)
{
  digitalWrite(13,HIGH);
}
else
{
  digitalWrite(13,LOW);
}
  if (hmed<50)
{
  digitalWrite(13,HIGH);
}
else
{
  digitalWrite(13,LOW);
}
  Serial.print("   ");
  Serial.print(h1);
  Serial.print(" ");
  Serial.print(h2);
  Serial.print(" ");
  Serial.print(h3);
  Serial.print(" ");
  Serial.print(h4);
  Serial.print(" ");
  Serial.print(t1);
  Serial.print(" ");
  Serial.print(t2);
  Serial.print(" ");
  Serial.print(t3);
  Serial.print(" ");
  Serial.print(t4);
  Serial.print(" ");
  Serial.print(hmed);
  Serial.print(" ");
  Serial.print(tmed);
  Serial.print(" ");
  Serial.println(tdif);
  delay(2000);
lcd.setCursor(0,0);
lcd.print("INT:");
lcd.setCursor(5,0);
lcd.print("T");
lcd.setCursor(6,0);
lcd.print(tmed);
lcd.setCursor(8,0);
lcd.print((char)223);
lcd.setCursor(9,0);
lcd.print("C");
lcd.setCursor(11,0);
lcd.print("Um");
lcd.setCursor(13,0);
lcd.print(hmed);
lcd.setCursor(15,0);
lcd.print("%");
lcd.setCursor(0,1);
lcd.print("EXT:");
lcd.setCursor(5,1);
lcd.print("T");
lcd.setCursor(6,1);
lcd.print(t1);
lcd.setCursor(8,1);
lcd.print((char)223);
lcd.setCursor(9,1);
lcd.print("C");
lcd.setCursor(11,1);
lcd.print("Um");
lcd.setCursor(13,1);
lcd.print(h1);
lcd.setCursor(15,1);
lcd.print("%");
}

The way you have it written if the temperature is off but the humidity is OK the buzzer will sound for less than a microsecond because the temperature check will turn it on and the humidity check will turn it off again.
You want:

  if (tdif<10 || hmed<50)
    digitalWrite(13,HIGH);
  else
    digitalWrite(13,LOW);

This can also be written as:

    digitalWrite(13,tdif<10 || hmed<50);