Support them financially
Once you reach a certain age, you won't have the strength to work how you used to. Some elderly folks are lucky to have sustainable businesses but many don't, and they need some financial support.
If you can, consider giving a certain amount for shopping every month. If this is a lot on you right now you can still decide to surprise them once in a while so that at least they will not feel abandoned.
Hire someone to help around the house
The elderly also need to have someone around who can help them with daily chores. Some might insist that they can still handle everything but, it will wear them out eventually.
Some of them might also need to be observed once their health starts deteriorating. They need someone who can watch them and help them out, and maybe you can organize that for them.
Encourage them to reach out
Elderly people often hate being treated like children. Some can be stubborn and you might not easily know what they need until you force it out of them.
The best thing you can do is encourage them to reach out if they're sick or when they need some support. This is how you can help them feel comfortable being vulnerable in case they need help.