Is it true baby younger than 3 months cannot bring the baby out? I was scolded by my mom for bring LO out to shopping mall. Because after I return home my LO keep crying and it become everyday thing. And she assume that is because I bring her out.

This is a myth that even I ended up following haha, my son only went out when he was 3-4 months old. I'd say that for a start, try to make short and quick trips out at times where it's least crowded to avoid overstimulation - which is what it seems like from your LO. A simple quick start could be a 10min walk around neighbourhood, or going out for a quick meal and then back! The lights, sounds and crowd stimulates them a lot, so if you go to malls, it's gonna happen a lot faster - a good guideline is that an hour outside is like 2 hours at home. If you are out for 3 hours, it's almost like being home for 6 to them!