I would ask the grandmother first if she was okay. Explain your concerns to her before talking to your employers.

Do the calls start around the same time each day? I don't pick up my phone when I get a call from MIL after seven PM (cocktail hour).

Good heavens. Yes, you tell your bosses. You should not have to deal with that (frankly, whether she's on pain medication, drinking, or just overstepping, you shouldn't have to be dealing with this level of contact with anyone who isn't your employer.)

But given your long term relationship with the family, and what sounds like it's a changing dynamic w/ the grandmother, then you should tell them for that reason also.

- MB

I've been with my awesome NF for 2 years. My charge and I meet up with DB's mother once per week so she can see him.
I enjoy her company immensley. She is a nice woman and easy to talk to.
Over the last couple of weeks, she has called me to set up plans to meet. She has been high when she calls. The way she talks and the things she says point to pain killers. I have a hard time understanding what she's saying. She's started calling me and asking if I'm mad at her, if she's inconveniencing me or if I like her. It's getting really weird.
When we get together, she acts totally normal.
Do I mention this to MB/DB or let it go?
I don't want to start any family drama, but I'm a bit concerned.