Is it necessary/customary to have favors for guests at adult’s birthday parties?

I had never really been to an adult birthday party until I met my husband’s family. His mom thinks that there need to be favors at every party. To me that seems a bit childish and honestly they usually aren’t even taken at all the parties of theirs I have been to.

My husband has not had a birthday party since in the last 4 years. I am throwing him a surprise party this year and am trying to decide if I need to do favors or not. His family will not help with any of the party cost, so it’s not like I could even ask them to take care of it.