C.D.
Well, I wish I had a sure solution for you, but maybe it will just help knowing that you are not alone. My hubby is Army and I spent a year living in my parents' basement when he served a year in Korea 4 years ago- my kids were 1 and 3.
When I stayed with my parents my mom was a wonderful help and rarely gave parenting advice unless I asked. However, my dad would make comments like "your letting your kids eat straight sugar!?" when he saw one of them eating some marshmellows or he'd wonder out loud why I let them run around in their underwear and little things like that. I learned to not get defensive which would make it worse- I just took his critical observations with a grain of salt.
He also likes things "just so" so he would sometimes get miffed if the kids got into his computer area or otherwise interrupted the order he was accustomed too. Again, I just tried to accomadate without getting upset- remembering that I was blessed to have parents that could and would gladly take me in. The benefits of having my parents be a part of my kids lives helping to fill the empty space a bit while their dad was gone and the benefit of saving money far outweighed any inconveniences. So that's where I'm coming from.
Onto, your situation. Just like with kids, choose your battles with your mom. Let the little things go. If the homework situation and the snacking are two very important matters to you then stick to your guns on that. There are bound to be some conflicts- grandparents have opinions and most likely think they are doing what's best even if it goes against your wishes. But your mom should respect that what you say goes. Just like a husband and wife need to support each other on discipline matters- or it encourages the kids to not respect either parents counsel. And ask for her support for the "greater good." Also make sure you let her know all that she does that you DO appreciate.
Looking at it from your mom's point of view- she may feel that you are in her home so she can help you and feels it is part of her job. If she helps a lot with child care you may need to make some compromises (just like you would with your hubby in order to keep the peace.) But talk it out and let her understand where you don't want to compromise-- like on the extra snacks. When your child asks grandma for a snack she may want to start saying "ask your mother" and then she needs to back you up with whatever you say. That way she doesn't feel like the "bad guy" which my be a concern to her.
Another thing that might help...Well, do you have a space you can call your own? Well, for me it was the basement. When I saw the kids were getting too rowdy or that my parents just seemed tired I could retreat downstairs and give them a break. You may want to set up a homework station in a bedroom or somewhere where your mom is less likely to interfere. When it's homework time, you and the kids who have homework retreat to that private area.
Well, I hope this was somewhat helpful. Hang in there and God Bless your husband and your family!
C.
PS- I think you are on the right track in your approach to the overabundance of homework. My 3rd grader deals with a similar situation. She may have a couple hours of work when her 1st grade brother just has 10-15 minutes. My daughter is very smart so I don't worry about a few low scores. Like you, if I see a low score I will just make sure she realizes what caused it and that in her mind she understands whatever principle is being taught. A lot of times I find that the wrong answers are just do to carelessness and rushing through-- which you can hardly blame considering the amount of stuff she has to get done. As long as you know your son is understanding the basic concepts being taught, I think that making a big deal out of low scores is going to be more of a negative than a positive. You don't want him to feel he is underachieving if he really isn't considering the circumstances. Maybe you can check with his teacher and make sure he is doing fine and keeping up with his peers. If you get that assurance, then I would downplay homework- sometimes good enough is good enough.