Seeking help on Switzerland itinerary for a week in early June

Is your mom in good shape, active and no trouble walking? That might be a factor on your choices and where to stay. From Montreux, you can take the Golden Pass route by train to Interlaken Ost. Most of us would recommend going further into the mountains, at least as far as Lauterbrunnen, and if you really want to see the Switzerland everybody imagines, go up and stay up on the mountains. Muerren is picture perfect, but Wengen is a better place to stay if you want to go to the Jungfraujoch. Stay at least 3 days and you might have a clear day to go up. It is expensive, so go early on a clear day. Clouds can build up in the afternoon.
The travel to Luzern for 3 days on the second half of the Golden Pass route. Pick a good day day to go to Titlis.

From Luzern you can get a train to Zurich where you can get either a bus or direct EC train to Munich. The bus is a little faster as it travels on autobahn and the rail line is a bit of a zig-zag and the tracks are not suitable for high speed trains. Nontheless, I think a train would be more comfortable for your mom. You can get up walk around, use the toilet whenever you want and there is a bar/restaurant car.

You can research the Swiss train prices at www.sbb.ch/en. There are passes, but almost always, the Half Fare cards for 120 CHF saves you the most money. You still have to buy tickets for every journey, but always with a 50% discount. For the trip to Munich, if you buy several months in advance, you can get very inexpensive nonrefundable tickets.

Thank you very much, Sam!
Actually, my mom has a diabetes and knee/back issues (I should have mentioned it), so we prefer only mild activities. I also thought about purchasing 8-day Swiss pass (quite expensive), but I will have to compare the prices for purchasing individual tickets with the half fare cards. Thanks again.

When you look up prices, note that the first price you see will be the price if you have a Half Fare card. When you click on the red ticket icon to the right of the train you want, it will show something like this:

Lauterbrunnen Luzern
Via Interlaken Ost
2nd class
1× Individual Tickets, Half-Fare travelcard
Valid: Mon, 26.02.2018
until Tue, 27.02.2018 05:00
from CHF 20.30

The actual price is 40.60 CHF without the discount card. Keep that in mind.

Muerren has quite a bit of walking involved. Wengen less so, especially if you stay at the Hotel Silberhorn, across the street from Wengen station. Its pricey, but your mom is worth it :-)
Interlaken is much further away with only a view of the mountains in the distance. A lot of big hotels, restaurants, access to boat rides on the lakes. Less expensive. Longer train rides to get to the mountains you want to visit.

I always like a map to plan. Here is a rail map for Switzerland: https://www.sbb.ch/content/dam/infrastruktur/trafimage/karten/karte-sts-pass-gueltigkeit.pdf

The "Golden Pass" route is Montreux - Zweisimmen - Interlaken - Meiringen - Luzern (look on the map), which luckily is exactly where you wish to go.
You have "7-8 days" for Switzerland (call it 7 nights), and your Mother I assume wants comfort does not want to walk far. I would suggest the following.

• Train Montreux to Wengen (in the mountains south of Interlaken). Stay 3 nights. This is a car-free town halfway up the side of the mountains. It is also on the train up the Jungfrau. Chill out, look at the weather forecast and pick the best day to go up Jungfrau. See this map of the area: http://www.regionalpass-berneroberland.ch/assets/karte-und-partner/Regionalpass-Panoramakarte-2017.pdf
• Train to Luzern. Stay 4 nights. Old town (no cars in centre). On lake with boat trips around lake. Three possible mountains to go up by train or cable car: Pilatus, Rigi and Titlis. See this 360° panorama of Luzern: http://tour.luzern.com/360/en/ The station is the building on the left of the bridge, with the boat landings in front of it. The old town is to the right of the bridge.

Skip Zürich, but you will have to change trains there on your way to Munich. If you want a city take a day trip to Bern. But this may be too strenuous for you Mother.

To get to Munich, train would be more comfortable than a bus. The Switzerland - Munich route is overdue for an upgrade (in progress), so it is one of the few routes where buses are similar times to trains. Usually buses take a lot longer.

You need to consider your ticketing options for Switzerland. Options are:
1) Full price tickets. With the amount of travelling you are doing this is almost certainly the most expensive option.
2) Swiss Half Price card (CHF 120 per person). Then all tickets are ½ price.
3) Swiss Pass. Then all travel in Switzerland is free, EXCEPT for the mountain railways on which you get a discount. You then buy a ticket from the last station in Switzerland to Munich.

Many thanks to both of you!
I really appreciate it.