Where are Carrefour, bigc and Lotus in Bangkok, Thailand?

Mkkasan has a subway station in Sukongvit (this is misspelled). BKK's subway is connected with the sky train BTS. I suggest you take the subway to Siam Palace Station and walk to Grand C, opposite the Central World. Siam and Central are both in the urban area, so you can still go.

Lotus is also found along BTS, which is generally a little far from downtown Bangkok. My last suggestion is that you go to BTS Sky Station and get a map of Bangkok with some big supermarkets on it, usually at the last stop of Sky Station.

Carrefour has one in sukongvit, which is the subway station between suttizan or Thai Cultural Center. You can ask the hotel waiter.

It is probably not feasible to walk to the big supermarket. Because there are many paths in Bangkok and it is crowded, if you are not familiar with the road conditions, I suggest you take a taxi, keep the Thai address of the hotel (you can ask the hotel front desk to give you a business card) and tell the driver that you are going to Da C or Lotus. They all understand. It is also possible to show your Thai address when you come back. Take a taxi 35Bt to start, but it's a bit blocked. So it is a better choice to consider the crown block or subway.