If I understand you right, you want to be able to ask the user to pick from a set of options, and get what option they picked.

Blocking

Until they pick an option, you can't do anything, so it makes sense for the ask() call to block (wait) until an answer is back.

ie, ask should not return until it has its answer.

gui = script.Parent.Options

function ask(...)
	local answer = nil
	for i, option in ipairs{...} do
		local label = Instance.new("TextButton", gui)
		label.Size = UDim2.new(0.5, 0, 0, 32)
		label.Position = UDim2.new(0, 0, 0, 32*i)
		label.Text = option
		label.MouseButton1Click:connect(function()
			answer = option
		end)
	end

	repeat
		wait()
	until answer

	gui:ClearAllChildren()

	return answer
end

local choice = ask("yes", "no", "maybe")
print("user chose", choice)

Of course, this repeat wait() loop is wasteful. It would be better to use a real event and :Wait() for it. You can use a BindableEvent for that.

function ask(...)
	local event = Instance.new("BindableEvent")
	for i, option in ipairs{...} do
		......
		label.MouseButton1Click:connect(function()
			event:Fire(option)
		end
	end

	local answer = event.Event:Wait()
	gui:ClearAllChildren()
	return answer
end

Promise

Sometimes it's an annoyance that functions block (in particular if there's multiple things going on at once).

Instead, you want the function to return immediately, but you want to say "...but when I get an answer, do this".

Promises are what you can use when a value doesn't exist yet.

A "promise" is a way of doing this. You return an event, and the caller just :Wait()s or :Connect()s to that event to discover the choice of the user at a later time:

function ask(...)
	loca event = Instance.new("BindableEvent")
	for i, option in ipairs{...} do
		......
		label.MouseButton1Click:connect(function()
			gui:ClearAllChildren()
			event:Fire(option)
		end
	end

	return event.Event
end

local onChose = ask("yes", "no", "maybe")
onChose:Connect(function(choice)
	print("chose", choice)
end)
-- OR
print("chose", onChose:Wait())

Callback

Callbacks aren't the best, but they're another way to do this.

It's similar to a promise, except that instead of being returned the event, you give the function to be called with the answer, and return nothing:

function ask(action, ...)
	for i, option in ipairs{...} do
		......
		label.MouseButton1Click:connect(function()
			gui:ClearAllChildren()
			action(option)
		end
	end
end