To determine the correct order of the conversation, we can analyze the dialogue cues:

1. **Minh: How has Manh been doing after two months in Taiwan?** (This is likely the starting question about Manh's well-being in Taiwan.)
2. **Lan: He has adapted well to the new environment and seems very happy.** (This follows Minh’s question, providing an update about Manh.)
3. **Minh: That’s great to hear! What do you think he misses most from home?** (Minh expresses happiness and asks a follow-up question about what Manh misses.)
4. **Lan: I think he misses his family and the food from Vietnam.** (This is Lan's response to Minh's follow-up question.)
5. **Minh: Have you spoken to him recently to check how he’s adjusting?** (This concluding question from Minh inquires about any recent contact with Manh to see how he’s doing.)

Based on this analysis, the correct order should be **D: c - d - e - b - a**.

- **c**: Minh's initial question about Manh.
- **d**: Minh's follow-up inquiry about how he's adjusting.
- **e**: Lan's response about what he misses.
- **b**: Lan's statement about Manh's adaptation.
- **a**: Minh's continued inquiry.

So, the answer is **D**.