import re
text = "\r\n1115492_23181_0_0.g.vcf.gz.tbi\r\n1115492_23181_0_0.vcf.gz\r\n1115492_23181_0_0.vcf.gz.tbi\r\n..."
m = re.search(r"(?m)^((?:(?!\.g).)*\.vcf\.gz)\r?$", text, re.M)
if m:
print(m.group(1))
aW1wb3J0IHJlCnRleHQgPSAiXHJcbjExMTU0OTJfMjMxODFfMF8wLmcudmNmLmd6LnRiaVxyXG4xMTE1NDkyXzIzMTgxXzBfMC52Y2YuZ3pcclxuMTExNTQ5Ml8yMzE4MV8wXzAudmNmLmd6LnRiaVxyXG4uLi4iCm0gPSByZS5zZWFyY2gociIoP20pXigoPzooPyFcLmcpLikqXC52Y2ZcLmd6KVxyPyQiLCB0ZXh0LCByZS5NKQppZiBtOgoJcHJpbnQobS5ncm91cCgxKSk=