I'd ask if there are cultural issues as well. Most responses seem to indicate that this is too much, but it may be a huge blessing in disguise. Let your m-i-l natter on about what your husband was like as a child, and ask her to teach you to make his favourite foods, ask about holiday traditions he loves, and plan these things with her. It may be grit your teeth time for some of it, and if the constant chatter is stressing you too much, even if it's loving, ask her if she's interested in a class at the local senior centre, or lectures at the library, or free concerts. If she's gone to a class in the afternoon, enjoy your nap!!!!
Also, your husband may find that she expects him to be home early from work, or not spend as much time with his car hobby...in short, that may either annoy him with the demands so her future visits are shorter, or it may get him into the habit of coming home early and doing things with you both...and after six months he may continue that when she's gone.
Also, in general, try to suggest things to do together that have to do with his love of cars. I'll admit to zero interest in cars myself, but I've had fun at antique car museums or car shows. By suggesting you make a day of it somewhere there, you will be getting closer to his hobby and might gain more appreciation for it. Who knows...maybe you'll even end up building a kit car with him some day.
*Also, it's totally fair to suggest a weekend trip to the closest antique car museum and stay at a great B&B and book a wonderful meal or concert in the evening. Just sayin'...it shouldn't be ALL about him.