You do not have to take any action. Property you inherit from your mother is your separate property, no matter how long you have been married. However, if you make payments for mortgage, insurance, taxes, maintenance with community property assets, the community might end up with a percentage interest in the house you inherit.
The response given is not intended to create, nor does it create an ongoing duty to respond to questions. The response does not form an attorney-client relationship, nor is it intended to be anything other than the educated opinion of the author. It should not be relied upon as legal advice. The response given is based upon the limited facts provided by the person asking the question. To the extent additional or different facts exist, the response might possibly change.
As pointed out, inheritences are your "separate" property, not part of the "community." Your mother should see an estate lawyer to create a trust or will to make sure she leaves her property in the most tax advantagous and trouble-free way.
Since your spouse can argue he contributed to house payments, upkeep, etc., during the marriage and is entitled to some interest in in, you may want a pre-nuptual agreement to protect your property that he'd otherwise be entitled to.
Don't draft you own agreement without advice from a lawyer, since what you want is peace of mind and you won't get that from doing your own legal work. Notarizations do nothing more than guaranty the genuineness of a signature, they do nothing for the contents of the document or its advisability or enforceability.
Lawyers are most effective for a legal issue when they can practice preventative law, as opposed to when they're asked to clean up a problem that could have been avoided. Don't use a service like LegalZoom, either - they charge only for the documents they prepare and they are clear that the documents they sell are "self-directed" and they're not providing any advice, they're assuming that you already know exactly what you need. If that were true, no lawyer would need to go to law school and practice for the years we do to learn our trade and no one would be on Avvo asking for advice.
If that sounds self-serving, look on Avvo to see all the people who go lawyer-free or try to do their own legal work and then find out later - often after it's too late or a lot of damage has been done, that they need a lawyer.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.
As the two earlier answers note, and as you already are aware, if you inherit property during your marriage, or bring property into your marriage, it remains your separate property unless you choose to add your husband's name to the title.
Things can get more complicated, however, unless the property is completely paid off (no mortgage) when you receive it, and you never do any improvements on it. Once you either:
make mortgage payments on property during your marriage, or
spend money to make improvements on the property during the marriage,
there is a significant chance that you are creating a community property interest in the property, and, in the event of a dissolution, your husband would be entitled to be paid for his half of that community property interest. These issues can be complicated; I generally spend an hour to two hours for a consultation with a client on these issues.
I suggest that you at least consult with an experienced family law attorney, with experience in providing pre-marital advice and preparing pre-marital agreements, and that you should be willing to pay for the consultation. It'll potentially save you thousands of dollars later. Depending on the details, you may or may not need or want a pre-marital agreement. As noted by the other answers, however, this is NOT an area you want to try and "do it yourself" on the cheap.