Depends on the in laws.
Rent - yes, possibly, if all are sane, reasonable people with an understanding of boundaries and husband not likely to go running back to mummy to sulk at the drop of a hat. If boundaries are crossed and too much "popping in" happens then you can escape relatively easily and quickly. Makes for easy access to family support if needed, be that babysitting, helping out after an op, plant watering, whatever. But you will automatically be the one expected to help the in-laws all the time as nearest, even if other relatives live close by. Swings and roundabouts really.
Buy - no way. Too hard to get away if it all goes pear shaped.