But, she abandoned the residence 30+ days ago. It's likely that under the law she is no longer a resident. Her name might be on the lease, but she may not be considered a resident any longer and if she enters without permission it might be considered trespassing, and taking something from inside might be considered burglary.
If she intends to go and get something, it might be best to have a police escort. If the ex refuses to turn over the crib, then she can take him to small claims court and let a judge decide whose crib it is.
I have seen people get burned when they try to recover their property by barging into a place where they no longer reside. Though, the OP's state may have different interpretations of this so she might want to speak to the police or to an attorney before she takes action that could end up with her going to jail.