Hi Barbara,

I took a look at the 1930 and 1920 census records for Washington DC and don't see the family you have named.

Interestingly enough - there is a Sarah Ann Richardson, listed as niece - staying with a family surnamed Clark, in Wake co. NC.in 1930.
She's listed as age 34, married at age 20 , born 1896.

Name: Sarah A Richardson
Age: 34
Estimated birth year: abt 1896
Birthplace: North Carolina
Relation to head-of-house: Niece
Race: Negro
Home in 1930: Buckhorn, Wake, North Carolina

There is an Annie Richardson in DC in 1920, husband is "Albert"
there is a woman living next to them - or with them - a widowed Mary Clark

Name: Annie Richardson
Age: 22 years
Estimated birth year: abt 1898
Birthplace: North Carolina
Race: Black
Home in 1920: Washington, Washington, District of Columbia
Sex: Female
Marital status: Married
Relation to Head of House: Wife
Able to read: Yes
Able to Write: Yes
Mother's Birth Place: North Carolina
Father's Birth Place: North Carolina
Image: 1134

These may not be the people you are looking for, but then again - they might.

Denise