Etiquette question regarding family memorial?

My mother in law has died. My sister in law is hosting a memorial luncheon at her house. Should I bring flowers to her house, or give her any gift since shes the one hosting the lunch? Should I send cards to my 2 sister in laws? Not sure what to do, because it's my husband's mother. I wouldn't expect... show more My mother in law has died.
My sister in law is hosting a memorial luncheon at her house.
Should I bring flowers to her house, or give her any gift since shes the one hosting the lunch?
Should I send cards to my 2 sister in laws?

Not sure what to do, because it's my husband's mother. I wouldn't expect him to send cards to his sisters, but should I be doing anything as a family/not-family member?
Update: PS the mother lived in a different country so the sisters will be there for at least a month
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