Guess it depends on your area’s COVID restrictions. Definitely outsource the venue – way to much work at home.
If you’re somewhere rural / warm – a barn you could hire?
Social bowls at a local club?
Scavenger hunt in a large space?
If you’re thinking a meal then either massive pots of a couple of stews, a BBQ or ask people to bring something to share. Definitely BYO alcohol though if you’re on a budget.
Or would a local vineyard / brewery do a reverse BYO (people bring their own food/ picnic but buy their drinks from the venue)?

What does your husband like doing? with COVID there could be a couple of parties. Like a progressive dinner or a group scavenger hunt.

100 people! That’s huge. With COVID restrictions changing all the time it might be best to plan something outdoors or where there is an option for some people to be outdoors. A local community hall could be a good option that has a park next to it.

Hire a room somewhere – local community Hall or Scout Hall – or have a BBQ at the beach or in a park!

Hire a hall through your local council, bulk shop at aldi or costco, use simple upcycled materials for decorations

Hire a room at a small bowling club – people cant outstay their welcome and your house wont get trashed since the party isn’t there.
See if they can cater and do finger foods – it won’t be overpriced compared to having it at home, and if people get hungry they can order their own meal.
Don’t put on a tab – everyone can buy their own drinks.
You don’t need to decorate if you don’t want but if you do just get some helium balloons from big w and scatter them around the room.

You definitely need to hire a venue of some sort, a hall or big room at a club maybe? Ask immediate family for donations towards hire costs instead of a gift?

How about a paintball party?

Just do a BBQ rather tbengifts ask.people to bring a,plate of food to share…my friend did this for her wedding.

Hire out a local pub room, usually they aren’t to costly and that way everyone can buy their own drinks at the bar.

Golf trip! Or laser tag

I just had my 40th recently so I decided just to have and adults only party with no kids. This was the best and I pick a place in the city where a package food and drinks. It was great just to have adult conversation without our kids.

If he belongs to a club they could organise something for you or have a bbq down the beach with a cricket game guys like to do that.

What about a boat trip that way you won’t have to worry it’s all taken care of but I know you would be paying per head. It depends where you live to where you would go.

Depending where you are and COVID rules a lot of venues will let you hire a room for limited outlay or in some cases free and then guests just buy their own food and drinks. Just need a few decorations.