What helps
If they are leaving because they chose to, one warm sentence is enough — without visiting on their behalf, without property advice. If they are losing a home, you do not congratulate them and you do not say they will 'land on their feet'.
A concrete help is named, and can be refused: a box, an errand. You do not organize their house. Afterward, you do not ask whether it is 'all unpacked' or 'all settled'.
The next month is not a follow-up on the lease or the works. It is a sign for them. The date is celebrated only if it is a celebration for them.
Concrete example
"If a specific hand would help, say so. Otherwise I'm just thinking of you."
Key takeaway
- The tone follows theirs: interest if it is chosen, presence if it is forced.
- You help without taking over the place.
Try next time
Before you write, see whether the change is chosen or forced — and do not use one word for the other.