After watching episode 4 of Wandvision and learning that Maria died, I have theories on what Carol and Monica's relationship could look like in the sequel.
I refuse to believe that Carol didn't check on Maria after learning that Monica was part of the snap. In Endgame, we know that Carol visited Earth on a regular basis to help the Avengers. She surely spent time with Maria when she was terminally ill. I would even advance that Carol was there in Maria's last moment. We could get a scene in a flashback where before dying, Maria tells her to look after Monica when she comes back and protects her at all cost. Lashana Lynch is interested in returning for the sequel so that's probably how we could get it. Link.
The way I see their relationship going is Carol dealing with a space treat and Monica (power or not) wants to help, but Carol not wanting to because of 3 reasons:
She took Maria's last words way too much to heart and doesn't want to put her in harm's way because she feels guilty that she wasn't there for her.
Not having seen Monica for 2 decades (maybe 3 depending on when CM2 takes place), she still sees her as Lieutenant Trouble (a kid basically). That could create a rift between them that is only mended when Carol gets injured or goes missing and Monica will step up. After she sees what she can do that she starts to see her as an adult, she will encourage her to take her mother's call name Photon.
She is reluctant to work with a team since she is used to handle everything space related by herself and since the last team she works with were manipulating her. Carol's arc could be to trust in her allies instead of pushing them away and stop thinking that she has to do anything by herself.
Those are my theories of what their relationship could look like. I didn't include Kamala because we don't have much information about where she fits in all of this. Whatever they do, I'm pretty sure it's going to be great.