A spouse may have certain rights to elect a statutory share of property if they were not left a sufficient share of property by will. Your facts don't indicate what estate assets may have existed besides the house and the analysis is very fact specific. Typically life insurance proceeds will not be included in an estate. The wife/mother you reference should immediately seek legal counsel to review the will (including the codicil) and determine what action to take.
In Maryland, people have freedom to legally exclude most family members (except a spouse) from the will and I am not aware of any Maryland statute by the name you reference. (You may be referring to a British law but such would not apply to a Maryland estate).
This post offers general legal information and does not take away the need to get specific legal advice.
