Beautiful flowers and/or chocolates for mum and grandma, of course―and a bottle for the BF's dad.
If you're stony-broke, buy some South African, Chilean, New Zealand or Australian wine, because southern hemisphere wine is almost always good, even though it's usually cheap.
If you're flush on funds, get dad either (1) a good single-malt Scotch or; (2) a decent blended Scotch. You will be 'family' in no time flat, even if dad doesn't like Scotch that much...he'll have a lot of friends!
Be yourself and enjoy the occasion!
if you're over 21 ... bring a Box o'wine with you ... who doesn't love wine at OLD LADY birthday parties.
If you're not over 21 ... then bring short bread cookies ... something she can enjoy days after the party.
Just give her money. She can buy what she wants instead of you giving her something she does not like at all
steak
I'm going to my boyfriends house for dinner. This is the first time I'm going to be meeting some of his extended family. It's his grandmother's birthday so there will be cake, but what could I bring? I hate to go places empty handed...