If you're not ready to take the step to a skilled nursing facility or memory care, there are adult day care programs that can care for them during the day while you are at work and you can get home nursing services a couple times a week for medication checks and things like wound care.
Physical therapy and occupational therapy are also good ideas to look into for the balance and instability issues as old age and de-conditioning can contribute to that a lot.
As someone else suggested, a medication list review to minimize the pill burden and eliminate drug interactions and side effects can be very helpful. All of this can be started with a visit to his primary care physician for referrals for PT/OT, home nursing, medication review, and caregiver respite things like the adult daycare. Just make sure to schedule a 30 to 60 minute appointment to make sure there's enough time to go over everything.
Note: for the medication review, don't be alarmed if the physician takes him off of things like blood pressure or cholesterol medications because those are more aimed at preventing complications, so if someone is approaching the end of their life anyways, there really isn't anything to "prevent" per se.