Possible positive signs in an istikharah dream

According to your description, seeing your late grandmother greet you warmly, hug you, and give you something may generally be viewed as a positive sign, symbolizing goodness, prayers, affection, or some form of blessing. Likewise, the fact that a stone was dropped from above but did not harm you could indicate that even if there are obstacles or challenges ahead, Allah may protect you from harm through His grace.

However, this is only a possible interpretation and should not be taken as a definite meaning. The primary purpose of Istikharah is not necessarily to receive an answer through dreams, but to seek Allah’s guidance toward what is best. Therefore, when considering marriage, you should base your decision on the person's religion, character, suitability, and sound consultation with trusted people. If the proposal is appropriate from both an Islamic and practical perspective, then a dream alone should not be used as the sole basis for either accepting or rejecting it.