I must admit I'm a bit bemused by this. It's really welcoming of you to have them stay for a month, but do you really need to cater exactly for what they would normally eat?
Isn't the whole point of visiting another country to try to eat as much of their food as possible and experience that way of life?
The not eating pork and beef I can understand, I would definitely cater for any religious or ethical dietary requirements. So like others have said, I would cook lots of veggie meals so you're not eating chicken or lamb all the time!
But not eating cereals or 'being keen' on sandwiches - shouldn't they be just mucking in a bit and eating whatever you eat? The first time I spent 6 weeks in Africa that's exactly what I had to do, and wanted to do. My hosts did ask for particular preferences or dislikes but we generally ate as they normally would, or where we varied it was in a way that was as little fuss for them as possible. So for example, they wanted to cook lots of egg-based dishes very early in the morning, which was just too heavy for me to eat every day at that time. So after a while we compromised and I just ate the bread and fresh fruit that was served anywy alongside the hot meal everyone else was eating. On the odd day I felt like the cooked meal, I joined in with the others. That way I was comfortable, and they were, and I didn't feel I was being rude.
For breakfasts I would try to have a selection of cereals, breads, fresh and dried fruit etc and let them get on with it. Perhaps try to take them food shopping and see if there is anything they see that they would eat in the mornings - but it has to be either no- or little-preparation or they have to be able to do it themselves!
Lunches - either sandwiches and let them acquire a taste for them, or lots of help-yourself type salads. Or serve the sandwich fillings separately with different types of bread, crackers etc. And lots of fruit again.
Don't spend a month wearing yourself out with all of this!