Full disclosure - I work in the funeral business.
We get cards a lot. They're always lovely to receive, and we put them on a wall of our office.
We don't expect a cash tip, but generally, if someone chooses to tip us in cash, it's around a fiver per staff member present - so, for a director, 2 drivers, 2 additional bearers, the general amount tipped is £25. It's enough for us to grab something to eat together once we get back to the office.
We personally tip the gravediggers £10 (which ensures that once a grave is filled, they arrange the flowers on top of the grave), and our local hospital £3 (for which they provide us with a wrapped sheet for transport, and height/width measurements so we can have the coffin made up more quickly). Some directors pass these costs on as "gratuities", some don't. Check your estimate to see if these costs have been included there or not.
Funnily enough, some of our ministers/celebrants give us a tip sometimes - fresh baked goods. Our humanist does a mean Mars Bar Rice Krispie cake.
Hope I've been of some help. Happy to chime back in if needed/requested.