You do not state whether or not you inherit any part of your uncle's estate, nor if the estate is still open. If you are to receive an inheritance and the estate is still open, you may have a right to contest the accounting. Contact a local probate lawyer to find out what your rights are. At the very least, you can ask if $20.00 was the actual amount of the life insurance proceeds and, if not, ask for an explanation of how the rest of the proceeds were spent.
If you are an interested party you have the right to certain information. Twenty bucks is a pretty small insurance policy for sure...however older people often have very small insurance policies from years ago and its also possible that it was borrowed against and there was only cash value left so it could be depleted. If you think it should be more you need to ask for documentation. Usually the life insurance is not part of the "estate" so it is also possible you won't be entitled to information but since its on the accounting I assume the life insurance ended up payable to the estate.
This is not legal advice nor intended to create an attorney-client relationship. The information provided here is informational in nature only. This attorney may not be licensed in the jurisdiction which you have a question about so the answer could be only general in nature. Visit Steve Zelinger's website: http://www.stevenzelinger.com/