Sounds like you need to contact a medmal attorney, however it will depend on what if any permanent damages your mother may have from the fall, as to whether or not you have a case worth perusing.
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It's hard to tell from your statement whether your wife suffered an injury specific to the fall (other than just a general bang to the head, etc). For example, I'd be curious whether she suffered a fracture or a subdural hematoma. If the fall happened and there was just a banged up head & bruising, i do not think you'd have sufficient damages to justify a lawsuit. this would change a lot depending on the nature of her injury.
See a local medical negligence lawyer and explain the full story. Hurry as the statute of limitations in California is just 1 year. A lawsuit must be filed in this period or the claim is waived. Good luck.
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