No, one adult is not required by the law to take another for medical care--even if the other is his spouse. However, he may not physically restrain the spouse (your mother) from seeking care; if he does try to physically prevent her, that could easily be a crime (ranging from simple assault to kidnapping to even attempted murder, depending on the exact facts). So your mother could have gone on her own for medical care, including by calling a cab if she couldn't drive, or even calling an ambulence or 911 if sufficinetly sick. Your mother does not need your stepfather to take her for medical care; she could have sought her own medical care.