Most jurisdictions, including councils and their relevant bylaws, prohibit any type of nuisance behaviour. It matters not if the nuisance manifests during day time or not. What matters in context of noise is frequency, duration, volume, intensity, droning and pitch. You, as property owner or tenant, have a right to the peaceful enjoyment of your property.

The council’s environmental health officer is typically the appropriate POC for these matters. They may ask you to provide a journal of events (you can write this retrospectively if this is a regular occurrence), and/or they may choose to attend themselves to verify during times in question or if you advise them as such.

Out of council hours, they usually ask for the police to be called so there’s a record/independent witness. There is nothing stopping you from calling the police during daytime.

The council may ask you if you’re comfortable to try and talk to the offending party to resolve the issue. Decline this vehemently and state that you fear for your safety (especially since this guy appears to be mentally ill!). Let them deal with the matter, it’s their job.

I feel bad for the bloke who’s ill, but conversely you do not need to suffer from his illness, and neither does your mum.

I wish you best of luck.