From the given information, we can create a table to organize the data:

Name Beverage Sugar Milk

Rumana Tea Yes No

Deepti Coffee Yes No

Osman Tea No No

Mahboob Tea No Yes

Masud Coffee No Yes

(Unknown) Coffee/Tea ? No

We need to determine what Waquar drinks, and whether they add sugar and/or milk to their beverage. We can see that there are only two people left who have not been assigned a type of beverage: Waquar and the unknown person. Since Rumana, Osman, and Mahboob all drink tea, we can assume that the unknown person drinks coffee. This means that Waquar also drinks coffee, since all six people drink either tea or coffee.

Now we need to determine whether Waquar takes sugar and/or milk in their coffee. From the information given, we know that Deepti takes sugar in her coffee, and Mahboob and Masud have milk in their beverages. There is no information given about whether Waquar takes sugar or milk in their coffee, so we cannot determine this with certainty. Therefore, the answer is that we do not know whether Waquar takes sugar and/or milk in their coffee. We only know that they drink coffee