**Explanation:**

In the given question, we are asked to identify the habit of Lushkoff. Let's analyze each option to determine the correct answer.

**a) Stealing:** Stealing is the act of taking someone else's property without permission. However, there is no information provided in the question that suggests Lushkoff has a habit of stealing. Therefore, option 'a' is incorrect.

**b) Telling lies:** Telling lies refers to intentionally providing false information. This option seems plausible as it is a common habit that people may have. Lying can be used to avoid punishment, gain personal advantage, or manipulate others. This option is supported by the phrase "Lushkoff is in the habit of" which implies a recurring behavior. Therefore, option 'b' is the correct answer.

**c) Working hard:** Working hard refers to putting in a lot of effort and dedication into one's tasks or responsibilities. While working hard is generally considered a positive attribute, there is no evidence provided in the question to suggest that Lushkoff has this habit. Therefore, option 'c' is incorrect.

**d) Making excuses:** Making excuses involves providing reasons or justifications for one's actions or failures. While it is a common behavior, the question specifically asks for Lushkoff's habit, and there is no information provided to support the claim that Lushkoff habitually makes excuses. Therefore, option 'd' is incorrect.

In conclusion, based on the information provided in the question, the correct answer is option 'b' - telling lies.