Did I "get" (or "take") my degree "from" (or "in") the University of Somewhere?

Firstly, a master's degree is not proper and therefore does not require capitalization, but personally I've seen several highly professional institutions spell it both ways.

Seeing as how all three of those sentences are grammatically sound, it's more a question of etiquette or regional custom. Like Peter Shor was saying, it's not wrong to say that you took your master's degree in somewhere but you may have to use caution repeating prepositions.

e.g. I took my master's degree in astrophysics in the University of Somewhere

Using in twice is potentially awkward in situations where you may need to elaborate on your area of study.

To answer your question, all of those examples are grammatically strong and should get the message across appropriately anywhere you go.

On an editorial note, however, there are some ways to bypass this dilemma by opting for more colorful words:

I (received, earned, attained) a master's degree after (studying in/at, attending, graduating from) the University of Somewhere.

Play it right and you'll sound like a Nobel Laureate, but all of your sentences will work well; none of them is really noticeably better, even on paper.

You took your degree at the University of Life.

You received your degree from the University of Life.

The reason is that you took it — as in studied for it — in the physical location. However the degree was awarded by the institution as an acknowledgement of skills obtained — not necessarily at the same place.

Never "in", at least not in the UK. That is reserved for countries and subjects. So you could say:

I took my masters degree in English at the University of Life in Belarus, and received my degree from there a year later, after further study abroad.