Take a hint;  It is personal: they just don't  like you.  You are never going to make them  happy. Invite your own parents over and whip a huge gourmet meal for them, spare no expense.  Then tell your in-laws all about how much you spend on your side of the family. Those parsimonious control freaks will be wanting their share of the money tree.

However, maybe they were exceedingly poor some time before you came along and they are still scarred by the experience of serious deprivation.   My own parents lived through The Depression,  and as  kids we experienced  the results well into the 1960s.