Help, please!

My dad passed away a couple weeks ago and I’m taking his cactus home. It used to live outside, in a south facing terrace, just like mine. (Same city, same weather)

The thing is that it has this reddish colour that doesn’t look healthy to me, but I have no clue if it’s too much water, too much sun…

I would be mortified if the cactus doesn’t survive, it’s kind of emotional as you may understand.

Can anyone help?

Sorry for the spelling, English is not my first language.

Thanks