I find the whole drama horrifying and sad. I wish the mom the best of luck and hope she gets the help she needs and not just lectures. Helpful suggestions/advice/ and actions help TONS more than some stranger saying, be a better mom.
I tend to not automatically assume the mom is at fault in a case like this since I DO NOT know her personal situation with dealing with young children alone with a loser father in the picture...in jail no less. Who knows if she is working full time/overtime (could be why she tried to kid proof the doors), is trying to divorce the man (or doesn't have the money to do so when you are basically a single mom...my divorce cost over ten thousand and went on almost three freaking years so I KNOW how hard divorce can be), has ANY kind of family support (lots of young moms don't), knows how the "system" works (more people do NOT realize what help is out there than you think...I know I didn't until someone just happened to mention the help available which I am forever grateful for), you don't know her education level (she could have had to drop out to support her kids). I mean the variables are infinite. It also doesn't mention if there are other kids in the house which is also another obstacle to take into consideration.
I mean I doubt that as a young kid...if she's 21 with a four year old she was still most likely in high school when she got with the father in the first place...went out of her way LOOKING to find a loser to impregnate her just so she could have some crappy life as a single mom stuck with a man in jail that is a horrible influence for her kids. Did she know the kids dad had a rap sheet? How many people do background checks as a teen to screen potential mates for future children you may or may not have?! I know I didn't! She most likely was immature (as ALOT of teens are), thought he was cute/smart/treated her nice/etc and by the time she saw his true colors or realized how dumb she'd acted thought it was too late to rectify the situation and just did the best she could with what she had...especially since by that time a child was in the picture and you tend to just survive for your kids you know? Plus again, who knows her personal situation during that time? How was her homelife as a teen? Did she slip through the school system with no teachers influencing her life? Unless you know ALL the facts and intimate details its a little hard to pass judgement or it should be IMO.
On a side note, I agree with PP who suggested a POSITIVE male influence...big brother organization and mentoring comes to mind. Sorry if I rambled on, hopefully I made sense...I just got off work and am a little tired.