Whether you are applying for Medicaid (called Medi-Cal in California) coverage of your wife's medical care, or Medicaid coverage for home care, or Medicaid coverage of her stay in a nursing home, that coverage can be retroactive not only to the date she applied but even up to three months prior to filing the application. Coverage applies to any of those months during which she would have met Medicaid eligibility requirements. There is a place on the Medicaid application to indicate that you are seeking retroactive coverage, and you must supply the Medicaid office with financial information -- your joint income and assets -- for that period. Check with the Medicaid office where she's applied to make certain that you have requested retroactive coverage. But even if you haven't applied for retroactive coverage, her coverage -- if she is found to be eligible -- will go back to the date of applying.
If you are confident that she will qualify for Medicaid, you can make an arrangement for her care knowing that Medicaid coverage will apply at least as far back as the date she applied for it. So, you have to determine whether she needs to be in a nursing home or whether instead you could manage to keep her at home if you received enough home care assistance from Medicaid. In either case, you need to find a nursing home or home care agency that accepts Medicaid payment, then discuss with them the fact that your wife has applied for Medicaid and that you are waiting for a decision. If a home care agency or nursing home is accepting new Medicaid patients or residents, they are likely to have a procedure whereby they could take care of your wife immediately on the promise that retroactive Medicaid coverage -- at least to the date she first applyied -- will become available. This may require that you provide financial information to the nursing home or home care agency, that you give them permission to contact Medicaid about your wife's application, and that you sign a promise to pay for her care in case she is denied Medicaid coverage.