When Nani took Sadhna for the job i think it was mentioned either to Mamaji or Malti that its a clerical type of a job and she is working in an office.
Mamaji was not given any address nor any phone number.
In yesterday's episode Mamaji went to someone's house asking for Sadhna and said she gave tuitions there.
In all this emotional drama maybe i am forgetting something or the creatives are.