My nana is interstate and I wish I could spend more time with her. She is now 75 but very immobile and uses a walker and her speech is not so good. She is in a retirement home and her energy to do outings for about an hour period only at a time. As I cannot be there to take her on regular outings to beach sunsets etc, I want to know if there are services/agencies that provide this in Sydney area
You might contact the county, or governmental jurisdiction in which Sydney is located, to determine if there's an elder group agency. I would contact Sydney municipal administration with the same questions. The New South Wales larger governmental unit might also have an agency dedicated to elder rights and issues.
I did a quick Google search and found this:
http://www.australia.gov.au/information-and-services/benefits-and-payments/older-australians
It might be a starting point. These "older" people groups are the kind you're looking for to determine what activities and services are available.
I'm wondering though since her physical energy is limited to about an hour whether outings from the facility (if the facility itself doesn't provide them), would be realistic for her.
Does the facility have music and art programs? Craft therapy? In my experience here in the Michigan, many facilities do have good programs. If there are none, perhaps you could speak with administration of the retirement home about starting some. If you have talents in that area, perhaps you could volunteer, even once a month or so since you apparently don't live close.
You could contact the activities director of the retirement facility she's in and ask about short trips out, and about other activities that might be available within the facility.
This is probably the safest and less fatiguing for your "Nana" since it wouldn't require the sometimes difficult transfers to get into a bus and go somewhere required by outings.