No. The mother is not obligated because the child is 18. And has, therefore, reached the age of majority in New Hampshire. (See below chart.)
Before age of majority:
- Parents are legally obligated to provide for the basic wellbeing of the child including but not limited to proper medical care.
After age of majority:
- Parents do not have any legal or financial obligation for the care and maintenance of children.
- Parents should not be paying or receiving child support payments.
Exception to Statutory Obligations
It is possible, however, that the parenting plan or custody agreement places extra-statutory obligations on one or both parents while child support is being paid. It would be important to read the parenting plan or custody agreement to see if that sets forth obligations for the mother not covered by statute. In which case the child could sue the mom for contempt of court or violation of the custody agreement (or whatever it might be called in New Hampshire) in order to enforce it.
Age of Majority by U.S. State
Source: http://contests.about.com/od/3/g/ageofmajority.htm
State Age of Majority
Alabama 19
Alaska 18
Arizona 18
Arkansas 18 or graduation from high school, whichever is later
California 18
Colorado 18
Connecticut 18
Delaware 19
District of Columbia 18
Florida 18
Georgia 18
Hawaii 18
Idaho 18
Illinois 18
Indiana 18
Iowa 18
Kansas 18
Kentucky 18
Louisiana 18
Maine 18
Maryland 18
Massachusetts 18
Michigan 18
Minnesota 18
Missouri 18
Mississippi 21
Montana 18
Nebraska 19
New Hampshire 18
New Mexico 18
Nevada 18, or if still in high school at 18, 19 or graduation, whichever comes sooner
New Jersy 18
New York 18
North Carolina 18
North Dakota 18
Ohio 18 or graduation from high school, whichever comes first
Oklahoma 18
Oregon 18
Pennsylvania 18
Rhode Island 18
South Carolina 18
South Dakota 18
Tennessee 18 or graduation from high school, whichever is later
Texas 18
Utah 18 or graduation from high school, whichever is earlier
Vermont 18
Virginia 18
Washington 18
West Virginia 18
Wisconsin 18, or if still in high school at 18, 19 or graduation, whichever comes sooner
Wyoming 18