50th Birthday Party ideas?

I'm throwing a surprise 50th birthday party for my mom at the end of September. I don't have a lot of money (I just got married and bought a house), so my dad is going to help pay for things like food. We're inviting about 40 people. I was thinking of doing more of a "celebrate life" theme with lots of bright colors instead of the traditional black over the hill theme, because I don't want to upset my mom! I could use some ideas. How can I keep it a surprise? Should I tell her that I'm inviting her over for lunch? (It will be a Sunday afternoon.) Also, is there anything I can do to make the party extra special? I was thinking of making a scrapbook of her life with pictures and getting everyone at the party to sign it. I've never made a scrapbook before but I think it might be fun. Thanks for any ideas!!

Do you have any siblings? You could tell her that just the close family is getting together for her birthday, then all of the extra people would be a surprise. That is what we did for my mother's 70th birthday.

I LOVE the idea of a scrapbook!! Maybe when you send out the invitations, you can ask people for a copy of a photo they might have with your mother in it and they could give you a little background about the photo?

I have 2 younger brothers. I love your ideas! I think I'll use both of them. I don't know how many pictures I'll get from my extended family because they are kind of lazy but any amount will help! Thanks!

I had a 50th party for DH in January-its a must to have a party in his family!!
Everyone know he hates-toads and frogs so of course he got lots of toad and frog things. Everyone always seems to get gag gifts (lots of the over the hill stuff). On my 40th one of my SIL got many of my old photos and photoshopped me doing various things with clever sayings.
It seems to come to do family, friends and food though!!