My wife hit her head on the floor 2 weeks ago. She haschattering lips and/or teeth - mostly when in bed. It may change to leg spasms or a hand will shaking. Is it serious?

Yes. Tremors like this can be serious especially hitting her head. Is she on any medications? Sometimes this can be a biochemical or neuronal imbalance. Please have her see a physician to get her balanced.
Donot neglect . These symptoms may be related to damage to the brain. Please do not disregard as she might have had a minor stroke before / during her fall. See your primary care physician who most likely will refer you to a neurophysician for an evaluation.
See a doc ASAP. Take her to see a general physician as soon as possible. It may or may not be related to the fall but it's not worth taking the risk. The general practioner will be able to lead you to a specialist who can determine if the 2 events are related.