вывести только те строки которые содержат: "Replied to question" можно так:
data = '''[auth][22.03 11:33:40] help
[auth][22.03 11:33:42] i'am admin
[auth][22.03 11:34:00] proceed command
[auth][22.03 11:34:04] Replied to question
[auth][22.03 11:34:05] txt
[auth][22.03 11:34:26] txt
[auth][22.03 11:34:26] Aboba
[auth][22.03 11:34:29] Replied to question
[auth][22.03 11:34:37] text'''
requested_string = 'Replied to question'
[print(line) for line in data.splitlines() if requested_string in line]
Как узнать, что в строке содержится слово?
print('hello' in 'hello world') 