Let's Rajani's age = R and her mother's age = M,and her father's age=F.
Acc. to Ques:
M=2R (Rajani's mother's age is twice that of Rajani)
F = M+10.
So, total age =R+M+F=160.
⇒R+M+M+10=160
R+2(2R)+10=160(substituting M=2R)
5R+10=160
5R=150
R=30
So, M=2R=2×30=60
So, Rajani's father's age is =M+10=70
Therefore, The correct option is (B).