Mother-in-law's clothes may be bought by her mother-in-law, father-in-law, groom or bride on their wedding day. The specific purchase depends on the local wedding customs. If the local wedding customs do not require it, it is usually the mother-in-law who decides what clothes to wear and then prepares the clothes to wear on the wedding day.
1 1 month, my mother-in-law wore many wedding dresses, which can be improved cheongsam+coat or down jacket, Tang suit, thick woolen dress, or a suit with coat. What kind of wedding dress to wear depends on the local climate, because the south 1 1 month is neither too hot nor too cold, so it is very comfortable to wear a long-sleeved dress suit. But it is already very cold in the north 1 1 month, so you need to wear thick clothes to keep out the cold.
On her son's wedding day, her mother-in-law can dress elegantly and try to choose more festive clothes such as big red and gold. As for the style of clothes, if you don't have any ideas, go to several dress shops and listen to the opinions of professionals.