df.to_csv("output.csv", index=False)

OR

df.to_excel("output.xlsx")

The .to_excel method writes a file and returns None. If you want the file content encoded in base64, read it back in:

import pandas as pd 
import base64

df = pd.DataFrame({'SourceNo':[11192,11193,11194],
                   'IssuedDate':['3/15/2021','3/15/2021','3/15/2021'],
                   'نوع':['هاتف','تلفاز','سماعة'],
                   'مكان الحدث':['حي السلم','منطقة الشمال','ميناء'],
                   'التاريخ':['3/15/2021','3/15/2021','3/15/2021'],
                   'أشخاص':['مواطنون','مواطنون','مجهول']})

df.to_excel('update2.xlsx', index = False, header=True,encoding='utf-8')

with open('update2.xlsx','rb') as f:
    b64 = base64.b64encode(f.read())

As of pandas-0.17, you can let Django write to a BytesIO directly, like:

from django.http import HttpResponse
from io import BytesIO

def some_view(request):
    with BytesIO() as b:
        # Use the StringIO object as the filehandle.
        writer = pd.ExcelWriter(b, engine='xlsxwriter')
        df.to_excel(writer, sheet_name='Sheet1')
        writer.save()
        # Set up the Http response.
        filename = 'django_simple.xlsx'
        response = HttpResponse(
            b.getvalue(),
            content_type='application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
        )
        response['Content-Disposition'] = 'attachment; filename=%s' % filename
        return response

You might need to install an Excel writer module (like xlsxwriter, or openpyxl).