Do you have an HR department? If so, I would suggest to the employee that she contacts them to explore what her options are as they should be fully informed of what policies may apply (eg parental leave, unpaid leave etc) and what would happen if she doesn't return as expected (eg disciplinary policy).
Has there been someone covering her maternity leave? Again, check in with HR about whether it is possible for them to be extended.
Don't suggest her working from home with a baby as a suitable option, even in the short term. Babies need attention and it is not appropriate for someone to be working whilst caring for them. Other may have had to muddle through it during covid when childcare was closed. That's not the case now.
I would think possible options are giving her a fixed time eg 4 weeks or 8 weeks of unpaid leave during which she secures childcare (some of which could be the child's dad). And keeping whatever arrangements were in place to cover her maternity leave in place for that time.
If she's unable to return to work ft, she needs to put in a flexible work request - eg to work part time or from home if that helps with childcare drop offs.
If she's a good employee, it would be short-sighted (of your manager) to refuse some leeway - any disciplinary process is likely to take some time to play out and in the meantime she's not there working, so may as well give her a few weeks to make arrangements.