can a muslim eat and stay for a night or two at Qadiani colleague's house?

Qadianis are not Muslims. The ruling of staying with a Qadiani at his home is the same as staying with a non-Muslim. If there is no genuine need to stay by the Qadiani colleague, then a Muslim should not do so. If there is a need and there is no alternative then the Muslim will be excused. The Muslim should exercise precaution when eating with non-Muslims as the food my be haraam or contaminated. He/She may eat vegetable meals that is not contaminated with any impure ingredients. The opportunity may be embraced to explain the Qadiani the correct Islamic belief with wisdom.

and Allah Ta'ala Knows Best

Mufti Ebrahim Desai
FATWA DEPT.