What is the best daily multivitamin supplement for the elderly. Is a liquid supplement such as Geritol the best for them?

If you believe that the elder you are caring for is not getting a decent balanced diet, then there is no reason you cannot give them almost ANY daily multivit. They are all somewhat similar. Choose a brand you like and go for it. I myself spent my career as a nurse, and I am not overmuch a believer in vitamins and supplements. Most are not needed in our western diets and are washed out in the urine.
I will caution people that taking vitamins and supplements is not a benign thing. They are not regulated by FDA or overseen much at all. Too much of a good thing is not always good. For instance, taking very large amounts of vitamin C and Calcium can actually cause kidney stones. I would say that a multivit every day is fairly benign. As to anything else, do pass it past your MD first. I believe in very very few supplements and vitamins. Just a Western Medicine gal, I guess.
Some people have deficiencies that need treatment; treatment is seldom adequate over the counter. For instance I used to run into elders all the time who had to take diuretics which wash out some of the potassium in their systems and can lead to serious heart problems. They would get the mistaken idea they didn't have to take the medication the doc ordered, and a banana would replace their potassium. Nope. Ended in hospital. So just saying, take care with this stuff.
Didn't even know geritol is still around. Remember ads for it when I was young, and I am far from that now!

jordanserb, I agree with what Alva had written. Next time the elder is at their primary doctor, have a blood panel done to see what vitamins the person may be low.

I have such a blood panel done yearly, and for me I am always low on Vitamin B12 and on Vitamin D. Thus, those are the only two vitamins I will purchase over the counter. I had to try out many different brands before I found a brand that wouldn't upset my stomach.

Oh, I remember those Geritol ads, too. "Feel Stronger Fast"

You can purchase multivitamins that are formulated for seniors that try to meet most of the minimum daily requirements and that omit vitamins/minerals that seniors no longer need (often labeled "adults 50+"). If the senior is being treated for low bone density, then calcium +Vitamin D is normally recommended--but there should have been a physician recommendation for that specific situation. I'd also run the multivitamin by the senior's physician. If the diet is adequate, probably the recommendation will be for no multivitamin. As AlvaDeer has said, vitamins are NOT benign, and the general medical recommendation is for no vitamins except to treat a specific deficiency or condition (such as one form of macular degeneration), If a senior multivitamin is recommended, try to get an inexpensive generic one; don't waste money on a brand name. I myself do take a generic senior multivitamin that I can purchase at Walgreen's in a bottle of 400, so it lasts over a year. In general, dietary sources of vitamins are usually the best ones, and the focus should be on a well-balanced diet, when possible, rather than a vitamin that tries to "make-up" for dietary deficiencies that could be best corrected by a change in diet.

Some of those multivitamin and mineral pills are big enough to choke a horse, if you feel the need to add a supplement then a liquid one might be easier to take.

I agree with Alva and FF.   I never considered taking a multi until a surgeon recommended it when I had a ruptured appendix.   I hadn't felt I needed it, but blood work dictated otherwise. 

And I think to be safe, it would be best to have blood work done for your elder.   We never really know which levels are normal and which are not.

If the person can still chew, try the adult gummy's. Luz used them to reduce the number of pils she had to swallow. She thought they were candy.